There are other enhancers that say to put them on any Item that gives you a combat bonus and aren't specific to "weapons."
However, since there are very few "shields" and quite a few "weapons," it's not that hard to make the decision to say a weapon is any Item that uses hands. However, you have a couple of choices:
- Use common sense; a shield is not a weapon. Nor is a Vehicle. Nor is the Item that is Armor in Star Munchkin that also requires a Hand.
- Follow the card, which says that an Item which uses a Hand or more can be enhanced by that card.
I mean, it's up to you, really. Personally, I'd say a shield is not a weapon, but that's just me. One could argue that one good old shield bash would convince we otherwise, but I'm steadfast in my resolve.