Personally, I like where this is going. I with DarkOrca. An idea like this should completely replace BR. To Crowley, the OP mentioned that the status effect would be applied by the class, not the skill, so that covers the "requires: X", but your concern is valid in the case that the status effect lasts long enough for a player to go through the motions of swapping class and rebuilding TP in the heat of battle.

The one thing I would suggest is making the skills only able to benefit from one other status effect, two at most. Otherwise they have a bit too much utility. Well, that's my opinion, at least.