Hmm, if you're looking to give a bat weapons...

What about something like metal claws or extensions that go onto the ends of the wings or onto the ends of the talons? It could be a way to enhance what they're naturally used to.
I remember a long time ago I played a fighting game with a bat-lady named Jenny, most of her attacks there emphasized using the claws on her legs and wings: https://www.youtube.com/watch?v=qdO0RvzfbsI


Another option would be some sort of short bow if he could manipulate it with his legs well enough, would be a huge advantage since he could stay flying without having to go into range of any potential enemies.

There's a few other older doodles of this guy with some wing/thumb like knives. Just toying with various designs, he's not supposed to be a great fighter.