To be honest, there doesnt really seem to be THAT much class/title synergy... tho i guess "of the nightfall" would add a bit of pizzazz to a warlock. Or, for that matter, a shadow priest if youre that way inclined. Not the easiest to acquire, however.
Personally i think that the two you mentioned, while certainly seeming to be aimed at druids/pallies respectively, work pretty well for other classes too... I'd love to get Guardian of Cenarius for my hunter, if i could be bothered trying to earn cc rep, because i think that it also fits well with hunter's involvement with nature... and in much the same way i feel like argent champion also works quite well for a priest. Seems to me that priests also enjoy busting out some holy wrath on undead nasties from time to time, so...
If those arent really your cup of tea tho, you could maybe go for "elder" from the lunar festival (quick!), and i think "the hallowed", from hallow's end, is also kind of appropriate for a priest. Might have to wait a little while for that one tho :)
I reckon you should just forget all of that and go for "salty" tho... ;)