Can Mage Hand be used in combat to grab something from an opponent?
For example, one could grab a bow out of their hands or the arrows from a quiver, or try to push them out of a tree, etc.
Mage Hand can carry up to 10 pounds, but what is its ability to interact in situations like these?
The basic text of Mage Hand says it can manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour the contents out of a vial. It cannot attack, activate magic items, or carry more than 10 pounds.
Disarming Attack1 is a special ability available to Battle Master Fighters or characters who take Martial Adept (PHB p168). Either way, it requires hitting the opponent with a weapon attack. Mage Hand cannot make attacks and is also not a weapon, so that's out.
Shove (PHB p194) is also an attack, so no.
Stealing other items requires looking at the things an Arcane Trickster Rogue (PHB p98) adds to Mage Hand.
• You can stow one object the hand is holding in a container worn or carried by another creature.
• You can retrieve an object in a container worn or carried by another creature.
• You can use thieves’ tools to pick locks and disarm traps at range.
If the specific rules2 for Mage Hand Legerdemain have to call out the ability to stow and retrieve objects from other people, then clearly the intent of the general case is that Mage Hand alone cannot manipulate objects in another creature's possession.
Mage Hand Legerdemain only allows for a Sleight of Hand (Dexterity) check to do the specific things it lists. It does not establish a general case for making ability checks with Mage Hand. An Arcane Trickster has to reach level 13 before he can even use his Mage Hand to be annoying, as a distraction via Versatile Trickster (PHB p98).
Can Mage Hand be used on an unattended object? Absolutely. Can it be used on an object in the possession of another creature? That's pick-pocketing, something that requires a Sleight of Hand (Dexterity) check. If taking things off a person is a basic object interaction, any character could walk up to another and take their arrows, and nobody could stop them.
1DMG Optional Disarm? Still an attack, still requires a weapon, still not possible.
2It may be worth noting that Mage Hand Legerdemain does not have the caveat of "open container" that Mage Hand does, another advantage that an Arcane Trickster has over a Wizard.
Can Mage Hand be used in combat to grab something from an opponent?
Yes, if:
No otherwise.
Mage Hand (emphasis mine):
You can use your action to control the hand. You can use the hand to manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour the contents out of a vial. You can move the hand up to 30 feet each time you use it. The hand can't attack, activate magic items, or carry more than 10 pounds.
Grab a bow out of their hands? Grab arrows from a quiver?
Although not directly an attack, this is considered disarming your opponent, which is an attack.
If your DM deems that it was not an attack, it would then be considered pickpocketing, which would require an ability check, which a simple Mage Hand wouldn't be able to do.
If it is an Arcane Trickster's Mage Hand Legardemain, you could also make an appropriate ability check (from NautArch's answer, Mage Hands allows for ability checks). Sleight of Hands to steal some arrows, for instance, or Strength to overcome his or her grip on their bow, as a couple of examples.
tl;dr You would not be able to use Mage Hand to grab objects out of an opponent's possession, unless it is of the Arcane Trickster Legardemain type.
Push them out of a tree?
This would be considered an attack, so no.
In other editions, the rules for disarming an opponent are clear. In 5, not so much.
There's an optional rule:
The optional rule for disarming (DMG p271) is as follows: A creature can use a weapon attack to knock a weapon or another item from a target's grasp. The attacker makes an attack roll contested by the target's Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.The attacker has disadvantage on its attack roll if the target is holding the item with two or more hands. The target has advantage on its ability check if it is larger than the attacking creature, or disadvantage if it is smaller.
But since it's assumed in 5e that picking up an object can be part of a creature's movement during its turn and can pick up before an attack, disarming becomes pretty pointless.
Since disarming is classed as an attack (this is specific to something in the opponent's hand) it is not allowed as part of Mage Hand. Same applies to pushing someone.
Taking arrows out of an opponent's quiver would actually NOT be an attack technically, as it doesn't take it directly out of their hand.
You can use the hand to manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour the contents out of a vial.
A quiver definitely qualifies as an open container.
Do keep in mind several things:
Here's the rules on interacting with an object--this applies to the person who is retrieving the object (NOT TO MAGE HAND). As you can see, it's a free action to pick up or take the object that's been taken by Mage Hand. But, at least, it uses up their free action.
The PHB (page 190)
You can also interact with one object or feature of the environment for free, during either your move or your action. For example [...] you could draw your weapon as part of the same action you use to attack. If you want to interact with a second object, you need to use your action. Some magic items and other special objects always require an action to use, as stated in their descriptions.
Although Arcane Trickster specifically mentions this as a special ability concerning mage hand, implying that it would not be allowed otherwise:
You can retrieve an object in a container worn or carried by another creature.
I would argue that an OPEN container, such as quiver that is easily accessible--not anything like a pouch or anything secured in any way (even a sword would be difficult) should be allowed.
Allowing it to be tried doesn't mean it will be successful. Since there is no check, if they notice it (and they will because it's obvious) they can prevent you from taking an arrow. (Keep in mind as well that it would be ONE arrow at a time). This, combined with the fact that it's a free action for the person picking up the arrow, means that the only thing you'd be doing gameplaywise is taking up a free action. You can try, but it's pretty likely that you won't be successful except as a distraction.
I think it depends on how you run your game, or how your DM runs your game. If you constitute an attack as any sustained force which can inflict at least 1 point of damage, then no, mage hand can't be considered an attack at 10 pounds of force.
The circumstantial "attack" is relative too. Pushing someone out of a tree only works if the person can't hold on, or is in a precarious situation. Some DMs will rule that spells not intended to cause combat effects cannot cause combat effects because they are explicitly written in a way as to only do X.
The spells in those games only do what the mechanics say, and the fluff is literally just that, fluff. However, if the DM runs the game in a more intuitive way, then a mage hand that pushes a guy balancing on the edge of a cliff could be fatal - but not considerably more fatal than the use of an illusional shout or growling monster over someone's shoulder in a tree that startles them causing them to lose their balance, and plummet to their death. In both cases, it was gravity that inflicted the damage, not the spells.
But some people rule an attack as anything that can cause damage. If you have a spell that ignites a combustible that triggers damage, and that spell, which we might call "Zippo" is defined as "cannot be used to attack" can that zippo light that fire? In some games, DMs would say no. These are not intuitive style games though.
Rules as Written are rules, yes, but those written rules still have to be interpreted. There's layers of interpretation, even when you take a literal interpretation. If you run your game like a video game, then there are spells you can cast over and over around the monsters and they don't even notice those spells because those spells are not attacks. The monsters do not notice them because they are only programmed to respond a certain way.
If you use mage hand to drop a vial of acid on a sleeping foe, does the vial automatically miss? Does the acid stop doing damage because you used mage hand to drop it? Where do you draw the line when a line like "is not an attack" is written? A pillow "is not a weapon" but people get suffocated with them every year. I think that really is where the line is: is your DM the type that runs the game so that under no circumstances, RAW defining all reality, a non weapon can never under any circumstance cause damage? An illusion without a listed will save can never influence a person's actions, and a spell not designed to do certain things can never be improvised?
I am not that kind of DM, but I will say, they do exist. Many are posting in this forum right now. So I don't even see it as a rules interpretation, this is more like an interpretation of the DM, because I have seen DMs where Mage hand is used offensively, and I have seen DMs where it is not, and both were following the letter of the law as far as they were concerned.
