I've outfitted him with an arquebus and the class ability that gives him a bonus with same. He is a back rank buffer/healer with (literally) a cannon! He also has a second level spell, can't remember the name of it, that fires in a line with a rather decent area of effect. It heals anyone on your team in the area and damages enemies. That's been very usefull. Granted, i'm only level 4 so i haven't delved into his midgame or lategame usefulness yet but he's not useless!