I found Anger one of the harder bosses to beat as his opening to allow you to attack is rather short and can you leave you vulnerable to damage.
When Anger shoots and then puts up his shield. Jump over him so he is facing away, being swords length apart. Raise your shield, wait for him to drop his shield and fire a shot, now drop your shield and hit him.
This was the only opening I found during his fight and obviously as he sped up the gap was smaller and lead to me getting hit a few times.