Remember this, among the buffs given out in the summer, Metatron was one of those who got some. Michael and Raphael didn't. Granted, Metatron's buffs weren't huge, but clearly she was considered to be underpowered while the other two weren't.

Raphael's A-frame atk debuff being 15% is fair given that it's paired with a % rage gauge reduction effect (Eros has 20% but it's stand alone) and doesn't have a noteworthy low rate of success (Kama's package of assorted debuffs). And since that's % reduction, it's an effect whose value scales up with tougher fights.
Overdrive orb removal at a solid hit rate is always handy utility.

Michael's... in a solid place, but I can't really say more than solid. +20 burst is nice, but its impact can vary wildly on the situation. Shingen builds would love it. Outside of Shingen, then it's a question of how much difference does that +20 burst actually make. Sometimes you want to burst on specific turns, and you may build up your burst meter in time without that skill anyway. Other times it's a lifesaver (worked out fantastically against Medusa, for example).
+light atk/+dark resist is basically mechanically alright against non-dark and very solid against dark. Because of how element resist buffs work, this is a skill fitting to be on an SSR.
Michael's basically in that place where I'd go, 'yea, she's SSR-level, but she's... just not a standout SSR'.
Having both Raphael and Michael, I'd easily kick out Michael first, unless I draw Eros, then I have to think about it.

Metatron's a Yet Another Attacker. The list of awakenings so far lean heavily in that direction.