Well... considering that most of their creativity for magical items rely on "IF" (if you do a specific action like dash, if you are on a specific surface, if you have less than 50% HP, if the target is a plant, if the target is burning,...) and on "Trade off" (a chance to fall asleep, deal damage to wielder,...), I guess there are a lot of possibilities to improve most items.
Won't make you a list but in exemple I'd rather like to find a sword that deal +1 damage on each attack or a shield that unlock a spell that deal 1D6 damage once/long rest than a sword that deal +1d4 IF I'm doing what Larian wants me to do.
