In one story, Karate Kid showed off his collection of hand weapons. There were quite a few, I think, that are recognizable today.
Hm, there was the Concentrator, which appeared twice. I can't really remember what it did exactly or who was trying to steal it the second time. Only that its second appearance was not in the actual Legion comic, and in the 70's.
IIRC, the Concentrator could concentrate all the energy in the universe for just a second, but it was enough to destroy some massive suns. I think it was in the first appearance of the Time Trapper.
Does the Miracle Machine count as a weapon? it could literally be used to do anything!
And should we count poisons as weapons too?