Basically the only reason why you'd invest in him is for the ice selection quest ... but within those parameters he's surprisingly good. The best MR ice unit once he gets that second master ability.
I like him a lot for maps with a lot a elevation changes. He has an innate +2 jump ( or +3 if you upgrade him ) that lets you get wherever and rain hell down with your bow. Plus the game gives archers more range when you’re at a higher elevation. I think he’s the only archer in the game right now that can get +3 jump