Health requirement removed
Reduced damage slightly so it won't be holy jesus OP
Make it give a debuff though, that lasts for say.. 6 seconds. You can't use hammer of wrath on a target effected by this debuff. - OR Make it give you a buff that lasts for 6 seconds, and having the buff prevents you from being able to cast hammer of wrath
The debuff / buff will in some way benefit your ability to do damage. I was unable to think of something, but I'm sure someone could say something cool that everyone would agree with.
The talent Sanctified Wrath(?) would have to be remade around this some how too though. Like.. maybe remove it's usage restriction or just effect a different ability that would benefit rets more than how it does now.
A second suggestion would be to change Holy Wrath instead of hammer of wrath with a similar idea as above.
Cooldown greatly lowered
Now attacks 1 or 2 targets instead of infinite.
Damage increased because it's damage is pathetic right now