I recently saw a cta built in a mace type weapon with +1 to HS selling for a lot. I am under the impression that it is for the prebuff of an extra +skill in HS. My question is, why would this be feasible?

Compare:
+1 HS CTA + spirit = +3 HS
+3 hoto + hoz/spirit = More than +3 HS

Why prebuff with the +1 HS CTA? What am I missing here?
I'm the holder of the that CTA, if you're talking about the Europe ScL realm. I didn't sell it.

Proud owner of the only +HS CTA on Europe Ladder Season 3.
http://img239.imageshack.us/img239/4...shot0198oh.jpg
It's rare and will not spawn normally.

Something I forgot to add, there is a bug which does make it possible for them to spawn, but is horrendously rare. Thrugg had a theory on it, which went like this: A staffmod is set to spawn on an item, and the second or third gets set to spawn the same skill as the first and gets reset, which would then allow the dis-allowed skills to spawn on that particular item.
Practical uses, well, I'm not sure if there's any. Astreon does the job in prebuffing.

If you don't fancy prebuffing though, it might be worthwhile on a smiter (Can't imagine any smiter carrying a HoTo)

Might also serve a use on mage builds, where the player does not want to waste a point in Holy Shield