Totting around a bunch of swords + stealth and parkour seems difficult given the inherent nature of it.
Question about the bit about: Ceruleum poisoning.
You make a point of saying his blood diluted it, does that mean it is slowly being worked out of his system (as it should if it were affected but such factors) or is it at a now permanent level? If it is the later, you may consider just nixing the blood diluting as an explanation as it just seems gratuitous (and confused me a bit). Another optional thing could just be that the ceruleum poisoning altered his aether permanently while damaging (or not) his general constitution (IE: damaging organs from their exposure). Doing so you could tie it into his aetheric outbursts, making it something that it's not simply about control but also permanent (again, or not) damage. IT could have also given him some sort of aversion or allergy to Ceruleum, now that his Aether has been permanent changed due to a reaction with it. Linking things into singular events rather than a string of coincidental issues/flaws.
Question about the bit about: Ceruleum poisoning.
You make a point of saying his blood diluted it, does that mean it is slowly being worked out of his system (as it should if it were affected but such factors) or is it at a now permanent level? If it is the later, you may consider just nixing the blood diluting as an explanation as it just seems gratuitous (and confused me a bit). Another optional thing could just be that the ceruleum poisoning altered his aether permanently while damaging (or not) his general constitution (IE: damaging organs from their exposure). Doing so you could tie it into his aetheric outbursts, making it something that it's not simply about control but also permanent (again, or not) damage. IT could have also given him some sort of aversion or allergy to Ceruleum, now that his Aether has been permanent changed due to a reaction with it. Linking things into singular events rather than a string of coincidental issues/flaws.