I am running the G series out of Tales from the Yawning Portal. The party killed a giant that had a magic weapon. This has to be a huge giant-sized weapon. How do you handle this? A weapon a giant uses like a sword that does 3d12 +6 damage, certainly cannot be wielded by a PC right?
I came up with this as a trade-off for wielding a Two-handed weapon one-handed....You could apply it to giant weapons in 2-hands in the same way, perhaps??
1) You cannot take reactions: Wielding the weapon effectively takes too much effort and cencentration
2) You cannot benefit from any Fighting Style benefits (2-weapon fighting, duelling, GWF)
3) You cannot wield a 2nd weapon.
Obviously as this would be a 2-hander, Number 3 wouldn't count. I'd maybe throttle back the damage a bit 2d12+STR isn't totally insane depending how far into the game you are, especially if it's at the cost of a fighting style. A lot I guess would depend on how important AOs are (enemies can just run past a guy with the giant weapon and eat the casters).
Conversely you could mimic the Loading property - or perhaps treat it similar to "Bad News" in Critical Role (i.e. 1 attack to set the weapon, 1 to attack - so a fighter with 3 attacks could attack-set-attack, then next turn Set-Attack-Set).
Perhaps require a successful STR check to attack (even a 20% fail rate is going to get annoying)
Just some ideas to get your juices flowing....