I noticed a clause in Bigby's Hand that has me pondering...
The hand lasts for the spell's duration, and it moves at your command, mimicking the movements of your own hand.
Here is the situation:
Bob is a 9th-level wizard. He is carrying his Wand of the War Mage +2 in one hand, and his other hand is open. Bob does not have the War Caster feat.
Bob casts Bigby's Hand and uses it to grapple a foe.
Does Bob still have a "free hand" to cast a non-concentration spell the following round?
Bob doesn't want to drop the Wand, as it is his spellcasting focus and he wants the bonuses. He doesn't have the War Caster feat, so he cannot "perform the somatic components of spells even when [he has] weapons or a shield in one or both hands." But per the spell description, Bigby will mimic the spellcaster's hand movements. So if Bob makes "a forceful gesticulation or an intricate set of gestures" with his other hand, does that mess with the grapple?
I've never seen a DM rule that Bob was out of luck with somatic spells, but I'm looking at this from a RAW perspective.
On the other hand, I can't help but picture the poor creature that's being grappled turned sideways while Bob puts his thumbs together to cast Burning Hands.