This is just my rough idea I came up with while thinking about how many times I have tried to make a hammerdin.
Paladin only weapon
Low base damage
Level 10 vigor while equipped
5-10% chance to cast holy bolt on striking
10-15% chance to cast searing light on striking
Low magic pen aura (or slight +/- magic)
+3-5 blessed hammer
+3-5 concentrate
This would be a cheap mans el druin, since the chances of getting el druin are slim to none, I'm basing these stats off the idea of making it a vanilla-style-drop.... You could always boost these stats and make it a rarer boss drop, but I can't be the only person that wants to see a Hdin work on annihilus 8)