A few things, you need some different ranged and close weaponry to help out, and some upper body training.

[Ivar's upper body is already pretty damn impressive, but it seems more brute strength than acrobatic or athletic skill, and that's what he wants to cultivate.]

Here, get on your horse and I'll show you.

[This would be easier with a mannequin to demonstrate on, but he'll work with what he's got.]