In the past, Blessed Aim was a no-go because it conflicted with Amazon’s Penetrate skill. Now I suppose its ok but you’re using Infinity that lowers Enemy Defense so needing Attack Rating is kind of moot. Prayer is only really useful if you have synergy auras as well(Cleansing + Meditation). You could use Cure but you won’t have Insight to grant Meditation so its not maximized. However, Cleansing is sooo nice to have for Amplify Damage/Decrepify and having double the Prayer output is nothing to scoff at.
Thorns was nerfed hard awhile back with respect to %Returned. Attacker takes Damage is nice I wont lie(since it procs on attack) but its not enough to warrant using it unless you were running a Necro/Druid with Summons and even then I would get it via Bramble. Might is kind of meh because the bulk of your damage is Lightning. It would help your Merc out I suppose but it’s not helping you so its up to you as I see it.
If you don’t use any of the above, that leaves Defiance and Holy Freeze. Defiance does boost your Defense(along with Merc’s Defense), but given you have Dodge/Avoid/Evade(without the dodge-lock), you don’t necessarily need it. Holy Freeze though is pretty good. Synergizes with Conviction and that slow is so strong on Bosses(provided you dont KO them instantly with Charged Strike).
Personally… use whatever you want, not what other people tell you to use. If you like Defiance, use it.