Can my character cast the Shield spell while carrying a sword and shield?

Question

I plan on taking the Magic Initiate feat with a paladin, giving him light, fire bolt, and shield from the sorcerer list. For light and fire bolt I can sheathe my sword as a free object interaction on my turn, then cast with my free hand, and redraw sword on my next turn to continue stabbing baddies; the same is true with all my other somatic spells. But since shield is a reaction, I assume that means I won't have time to sheathe my sword and do the somatic aspect of the spell in time?

Technically, could I get around it by always sheathing my sword every round that I'm expecting to take a big hit?

I want to RP that these are additional spells I've been gifted by Bahamut or a powerful dragon (I'm dragonborn), since they all make sense as holy abilities. Probably best to talk to my DM and see if they'll just let me use it without having to say "I sheathe my sword" "I draw my sword" 100 times? Plus it is only once a day, so not crazy OP.

Answer 1

It's Possible, But Tricky

You've correctly identified the difficulty of "sword and board" characters casting Shield. Shield is a great example of a spell that justifies the distinction between somatic and material components: it's a spell that is easy for non-shield wielding squishy spellcasters to cast, but difficult for the heavily armored heavy hitters (even those that can use a shield or weapon as a spell focus).

You could try dropping your sword at the end of every turn (this wouldn't cost any kind of action, as JC has clarified in tweets) and then be able to cast Shield as a reaction, and pick up your sword at the start of your turn. But this risks the possibility that an enemy could pick up your sword during their turn (either attacking you with it, or running away with it, or throwing it off a cliff etc.). That'd also stop you from making Opportunity Attacks with your sword (which also take your Reaction, but might come up on different turns than the need to use Shield).

The safest option is to get the Warcaster Feat, which would also give you advantage on Concentration Saving Throws.

Answer 2

By the published rules you need your hand free to cast shield as it has somatic components and no material components. From the PHB pg 203

If the spell requires a somatic component, the caster must have free use of at least one hand to perform these gestures.

If the weapon or shield was your arcane focus then you could cast a spell with both somatic and material components but not one with just somatic. The details of the reasoning was covered in this question. Though in the scenario given you could not use a arcane focus as that is a feature of the sorcerer class, and as a initiate you would have to use spell components not a focus.

What's the mechanical difference (as related to somatic components) between a holy symbol on a donned shield and a focus held in the hand?

Technically you could store and draw your sword every other turn but it does seem lame from a RP standpoint. I would think most DMs would be fine with it for a once a day ability. As Gandalfmeansme pointed out in his answer you could drop your sword every turn and pick it up as your free action but also seems silly from a RP standpoint and anyone else could also pick it up.

Answer 3

Yes, if you're a Githzerai or Artificer.

The Githzerai race has the Githzerai Psionics ability, which let's you cast the Shield spell without needing components once per day, once you hit level 3. This would allow you to freely cast the spell while weilding a sword and shield.

Similarly, an Artificer treats all their spells as though they had Material components, and must cast them using a Focus; they are furthermore capable of treating any item that they have used their Infusions ability on as a Focus. This means that if they cast a spell that requires Somatic Components, they will be able to perform them using the hand that is holding the Focus, as per the normal rules for casting a spell with Material Components. If their sword and/or shield were infused, this would allow them to cast the Shield spell with a sword and shield equipped. While Shield isn't on the Artificer's base class spell list, it is on the spell list of two of its subclasses: the Artillerist and Battle Smith.