Hey, not EVEN Iceman himself knew that. And that's all because he joked around more than trying to see where his limits can be pushed up to. He remembered all that stuff that happened to him while Emma was in his mind. And he tried many times to have her tell him how to do it.Of course, these where the times when Emma really got like, all morally and stuff, and told him these where things he had to learn to do himself. Then there was that one time, where he had a whole in his chest (in his ice form of course, and how he got it, I can explain if someone wants), he was scared to go back into his human form because he might die with the whole there. And after freezing the blood flow to Emma's head for a few seconds, and after mind games from Emma, Emma finnally got Bobby to revert back, and the whole just ended up as a big tear in his suit.
There's just so many things that Iceman can do. If the writers can touch on some of these, rather than just have him piss of Havok and others, it would be better.