Heh... yeah these things although pretty cool in conception are pretty nightmarish and inpractical in a massive online game. Not only is the code just annoying, but there are conditions for each character which always break rules.
If you have something to enchant, use your deity's or a friendly/allied/neutral one if you can't get to your deity's temple. Kinda simple. But never box characters. Maybe there is a reason why that particular cleric of Mist can safely use the pool at the Branderback temple, even though they are unfriendly to each other. Granted, not every case will be like this but if we start boxing characters in small limitations, soon we'll start putting way too many restrictions that I personally do not feel are necessary.
That's just the way I see it of course. Oh and bards/rangers/druids can enchant if they get the holy water from a friendly cleric, so you dont necessarily need to follow a deity. In those times they sold holy water at each temple, so there is no issue why random bard X goes into the temple of deliar, drops 25 gold for some holy water and uses their pool to enchant. Granted we dont sell holy water at merchants for CNR reasons but the point stands.