If we were to remove a few buffs from cleric, let's say, 12 buffs to 6 buffs or 3 (i'm perfectly fine with it), then the cleric should be given a few offensive capabilities. It's defensive side can be upgraded at least. With a proper build, it can withstand a few hits from other players, in cases of PVP.
Why not a skill that deals damage and decreases the opponent's mdef, but also decreasing your mdef, but since you are a cleric, your mdef will still be superior. I know there's a skill that decreases mdef of an enemy, but to learn it is to sacrifice a useful skill for a cleric.
Or to get the cleric's def moving a bit more, why not change Mystic Armor from 3 Def per x Intelligence to 3 Def per x Charm? We can go to as far as 3 Defense per 1 Charm, but it might move the cleric's defense from too less to too much.
what if those unique buffs who contain more then one buff at one become part of the normal skill tree?
that way we have this those req others want to keep but more sp left to spend in def passives?
that way FS cleric can survive just like war clerics .
btw i love your idea about the mystic armor!! thats really a good one i think .