User blog comment:D2r/Unanswered Questions of Redwall/@comment-217.30.122.155-20100201200459

Also, perhaps the hares of Salamandastron were able to forge weapons, after all, Col. Clary, Brig. Thyme and Hon. Rosie in Mariel of Redwall knew how to construct longbows - this may suggest that they knew how to construct other weapons as well.

Also, again on the matter of vermin tribes, Groffgut has a band of water rats under his control in High Rhulain, presumably originating from Mossflower. It wouldn't surprise me if there were various other groups like this in Mossflower counrty and beyond. Accumulated together, these vermin could form a sizeable army.