Sorry, Kenny, but there is no easy way around it. All I can suggest is be ready to dodge most attacks- you can block the arrows but when his horse rears up and start charging be ready as you cannot block the attack with the mallet or the charge.
Once you have killed the horse his next set of attacks are all blockable. The third wave of dead barbarians he sends has a special color to him as he is the "captain". You can get some green orbs from this one. Killing all of the barbarians he summons will move things to the final phase.
This is where things get interesting- in this final phase you will not be able to block any attacks. On the plus side, he will be limited to axe swings and ground-pound attacks. You will need to pick your shots and whittle him down while dodging. Eventually he will shrink down in size again. Eventually you will be able to get into the action-sequence mini game, struggling to get the hammer from the king. When you do he will charge at you. Kratos will lay 3 big whacks into his head to finish things.