There're many options:
a)
1 Cleansing (to remove curses/poison faster),
1 Vigor (to move faster, especially combined with Charge),
1 Redemption (to remove bodies so they can't be resurrected and some for life/mana regeneration),
1 Salvation (the rescue in dangerous conviction/LR situations)
1 Defiance (prereq. and synergy to Holy Shield),
1 Prayer (prereq.)
This set of skills is very useful, especially for certain areas (Baal runs for instance). Still it's only six points which leaves quite a bunch of points for other uses (for the high level Zealot). It can, in other words, be combined with any other option I've listed here.
b)
Invest the remaining points in Defiance to synergize Holy Shield. This is perhaps the most common choice.
c)
10+ points in Resist Lightning (Cold and Fire is not worth it IMO). 10 points means a maximum resistance of 80% instead of 75%, which may not sound like much but can make a huge difference. 5 more percent units lightning resist and ~15MDR can make the whole Gloam business a lot more comfortable.
d)
Blessed Aim for additional AR, via the passive bonus. I would only choose this route if CtH really was a big issue and if there hardly were any other ways to improve it. That's seldom the case with a Zealot.
e)
Invest the remaining points in Smite to improve the capability of fighting bosses (especially act bosses).
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