[@Kost Alter]Avenger is an extra class though. It has unique abilities that only it has oblivion correction being one of them. Fitting, or not it is a skill for a class that is normally not even able to be summoned. It would believe it should be replaced in my own opinion. 

I believe rank EX is presence concealment is rather high it is literally unquantifiable. As such it should be lowered in my opinion unless someone else believes that it should be that way. Likewise if they're doing physical damage to servants they should be able to be killed and thus dissipated in some sort of fashion. I have to keep in mind the enemy servants or possibly the masters are being hassled by these things while they're away from assassin.