How does the Thief's Fast Hands feature interact with mundane and magical shields?

Question

I have found this Q/A explaining some items a Thief can use through their Fast Hands feature as well as this tweet (though now unofficial) from Jeremy Crawford saying that Fast Hands does work with a shield.
The Fast Hands feature's description states:

You can use the bonus action granted by your Cunning Action to... take the Use an Object action.

And then the "Use an Object" section states:

When an object requires your action for its use, you take the Use an Object action...

The DMG (page 141) states this about activating magic items in particular:

If an item requires an action to activate, that action isn't a function of the Use an Object action, so a feature such as the rogue's Fast Hands can't be used to activate the item.

Shields require an action to don or doff and "Shield, +1, +2, or +3" are listed under the "Magic Items" section of the DMG on page 200.
However, it is still unclear to me whether donning/doffing a shield counts as either "Using an Object" or "Activating a magic item", so I am wondering:

How does Fast Hands interact with mundane and magical shields?

Answer 1

You can use Fast Hands to equip a shield.

In the Player's Handbook, on page 193, the Use an Object action says:

When an object requires your action for its use, you take the Use an Object action.

A shield is an object, and donning or doffing a shield requires an action, so it seems to fall under Use an Object, just like any other object use that requires an action (such as pouring out a bag of ball bearings). As such, it should be valid for Fast Hands to accomplish that as a bonus action.

Whether the shield is magic or not makes no difference.

Equipping a magic item is not the same as activating it. The Dungeon Master's Guide (p.140-141) discusses "Wearing and Wielding Items" and "Activating Items" as separate headings:

Using a magic item's properties might mean wearing or wielding it. A magic item meant to be worn must be donned in the intended fashion: boots go on the feet, gloves on the hands, hats and helmets on the head, and rings on the finger. Magic armor must be donned, a shield strapped to the arm, a cloak fastened about the shoulders. A weapon must be held in hand.

This makes specific mention of donning armor and shields, but no mention of it being anything more than the normal donning action.

Activation is an entirely different sort of action:

Activating some magic items requires a user to do something special, such as holding the item and uttering a command word. The description of each item category or individual item details how an item is activated. [...] If an item requires an action to activate, that action isn't a function of the Use an Item action.

and, under the item category listing for Potions:

Drinking a potion or administering a potion to another character requires an action.

So "activating an item using an action" is when the item's description or the item's category specifically calls out that activating it is an action.

Arguably, a magic weapon is activated when it is used to make an attack, and magic shields or armor are activated when the wearer is attacked, but whichever way you go on that, it still wouldn't stop Fast Hands from working with the item.

Answer 2

There is no interaction - you aren't using it, you are donning it.

Using an object covers:

You normally interact with an object while doing something else, such as when you draw a sword as part of an attack. When an object requires your action for its use, you take the Use an Object action. This action is also useful when you want to interact with more than one object on your turn.

The question is does donning a shield equate to "requiring an action for its use". However, you aren't 'using' a shield with the action - the shield provides it's +2 AC when donned - there is no action to use it.

The action for donning is not using, but simply:

This is the time it takes to put on armor. You benefit from the armor's AC only if you take the full time to don the suit of armor.

The act of donning the shield takes an action - hard stop. It isn't 'using' the shield that would call it "using an object", it is simply the amount of time it takes which equates to approximately 6 seconds.

Because you're not using it and the donning rules are just to cover the amount of time it takes to put on or remove shields, you can't use "Use an object" to don or doff. You must use your action.

Another way of looking at this is that you wear a pair of pants. I don't think you say "I'm going to go use pants" in the morning. Wearing and using are different things.

This is supported by the language used in Chapter 5 of the PHB regarding armor. It's never about using, it's all about wearing.

Anyone can put on a suit of armor or strap a shield to an arm. Only those proficient in the armor's use know how to wear it effectively, however. Your class gives you proficiency with certain types of armor. If you wear armor that you lack proficiency with, you have disadvantage on any ability check, saving throw, or attack roll that involves Strength or Dexterity, and you can't cast spells.

Answer 3

Donning or Doffing a shield requires an action

Donning or doffing armor is separate from the "Use an Object" action. Notably, a shield is the only kind of "armor" that takes 1 action to don or doff. The rules for donning and doffing are pretty clear:

Don. This is the time it takes to put on armor. You benefit from the armor's AC only if you take the full time to don the suit of armor.

Doff. This is the time it takes to take off armor. If you have help, reduce this time by half.

It doesn't name any kind of action, it just says that this is how long it takes to don/doff the armor/shield. Notably, it stresses that you only benefit from the armor if you take the full time to don it. Donning or doffing a shield is mechanically the same as donning or doffing armor, with the only difference being the time required to do so. The fact that the don/doff time for a shield happens to be the same as the time required for Use an Object doesn't make it an instance of Use an Object.

Donning/doffing a shield is not "using" it

You use a shield by putting it between you and an incoming attack. Mechanically, the shield is automatically used every time something rolls an attack against you, and this use is represented by the static +2 bonus to AC. You can only use the shield in this way if you are wearing it (i.e. you have spent an action donning it). No action is required to use the shield in this way, so the "Use an Object" rules do not apply.

There are some features that give you ways to use a shield with your action, bonus action, or reaction, such as the Shield Master feat or the fighter's Protection fighting style. However, all of these are special actions on their own, not "Use an Object".

If you wanted to improvise the use of a shield to do something like using it as a lever to pry open a stuck door, that would be an instance of "Use an Object", since it is not covered by any of the specific mechanics of shield use.

Magic shields are no different, unless they say so

Donning or doffing a shield is not considered activating a magic item. The only time you can activate a magic item is when the item's description describes an action you can take to activate it, as described in the chapter on magic items (emphasis added):

Activating some magic items requires a user to do something special, such as holding the item and uttering a command word. The description of each item category or individual item details how an item is activated.

A standard +1 magic shield doesn't describe any way of activating it, so the rules for activating magic items have no bearing on it.

Answer 4

You can almost definitely doff all shields

So, all item-use-actions are Use an Object unless expressly stated otherwise, since Use an Object gives itself that super broad mandate you've quoted in your description. The question, then, is whether taking a shield off is 'using' it. It seems like it should be, because in-fiction you're using the belt dohickeys on the straps to release it from your arm, but maybe your having to take an action here has nothing to do with interacting with the shield at all in your DMs world, in which case it might not be a 'use'.

Magic Items, of course, do have an exception, as you've noted, but that exception is much more restricted than 'use': it's only for 'activation'.

Doffing a shield, even a magic shield, can hardly be considered an 'activation', even if it is an action taken to use the object. Magic Items do not have an exception for items that require an action to deactivate.

You can probably don magic shields, and definitely* don mundane ones

Donning a shield is definitely* using it, but now it might also be activating it. 'Activate' isn't typically used this way in English, so you are probably okay, but it's definitely closer than for doffing. Mundane shields, obviously, don't have an exception even if it is ruled to be an activation.

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• Okay, so apparently at least some people believe employing a shield defensively is somehow not using it. While I've never encountered this interpretation before, particularly given this tweet but also just how consistently the word 'use' is used with regards to the employing of shields in combat-- this Ngram puts 'using a shield' at mostly between a half and a seventh as common as 'ate potatoes' across the last 200ish years, and this Ngram puts it as about twice as oft used as 'wearing a shield'. But still, maybe your GM is weird, and you should definitely ask them if shields can be used in combat or not in their campaign.