I like it, but I'd suggest a few tweaks:
>>bigger radius, like within 30' of caster (keep in mind the undead still have to fail a WP save to be affected)
>>how about 1d6 rounds +caster level?
>>cowering also removes Dex bonus
>>outright destruction of undead 4(?) levels below the caster
>>call the Good version "Turn Undead", even if it doesn't work exactly the same
>>I don't like Sacred Vigor so much. In KotC it's already easy enough for Clerics to heal people.
Unrelated: How about allowing evil Clerics to create undead right on the battlefield?