Query about dragon blood

I recently done the mch quest line and idk how the the baroness was able to usev"blood of the dragon" then turn back into an elezen in the proceeding cs if this is meant to be a specific spell glamour then it has a very bad name giving the context of ishgardian blood and this isn't only time it happens back in ARR the fake inquisitor you fight also does this turns into a dragon then following cs back to normal.
Whereas when searching for ice heart and we reenter the amphitheatre the ones that transformed stay transformed afterwards it's inconsistent but if there is any explanation for it I will gladly take it as my head is baffled by this

It seems as though at this point what we're meant to take away from it is that you can get away with it and still be human a limited number of times, but eventually it takes hold and you can't go back.

Ok it's just I wish something like that was actually said in game as it's a bit confusing to see dragon then elezen