I would personally wait for whatever drops I get from coil, and then plan out whatever mythos gear to buy. I was "forced" to level a palladin and I neither purchased either of the +1 to sword and shield, nor bought the mythos chest, and I could still tank/maintain aggro as per normal. Of course, your rotations and the timing to pop your buffs would have to be stricter.

That was just my advice, by no means would you have to follow it or treat it as law.