When I did the crafting, I indicated the greaves are water elemental, although I guess in the drawing, all the magic looks green. I am thinking that he channels a part of his magic power into the armor, and it might well be used by the armor to shield him from some elemental damage, but he'd still be able to use ice spells, so long as he has enough magic power left over that's not drained away by the armor. Particularly after all that training, it should be easier.