This guide may contain spoilers, so beware.
After you beat Hades and get the Claws of Hades you will have a chance to test out its magical attack. But instead of doing that you can get the Hit Man Trophy. I did this on Normal difficulty.
1. First off DO NOT upgrade the Claws, you do not want the “test” to end prematurely.
2. Once the swarm of enemies pop up, attack using L1 + O (circle button). Kratos grabs enemies with the claws and pulls out souls that attack nearby enemies. Make sure to keep doing this move.
3. After a while you may be overwhelmed by the enemies, in that case dodge/jump out of danger only after you attacked using L1 + O; while the souls attack the bad guys the combo meter will still be climbing as you catch a breather.
4. In about 20 minutes or so you’ll get 1000 hits and then the Trophy. Congrats!