But you're equating mantle acquisition with transfiguration. They're objectively different processes.
And subjectively the same, it's the same world mechanics acting in a streamlined fashion, on the jim butcher appreciation community on FB Jim wojed recently to someone asking about if Archangeldom was a mantle his reply was to the effect of,"it's almost like the rules work consistently in the DF" I can point out these consistencies and the why forth of it usually. Mantles and angels being similar, even other ranks of angels we are unfamiliar with all aligns with the beacon/possession/replacement process as seen in Rasmussen. Possession being the most damaging in it's relation to free will. But the original beacon is always at work, even Kravos came in through the Dream realm, through the mind.
Moving on from some things I've explained before, Rampires work the same but manifest differently. Instead of a shadowy hunger being born through you in your mind/soul, the damage is used to create the mirror directly through said transmogrification effect. they don't directly replace said person, but the mirroring in form and in hunger allow the continued assault by their personal demon/shadow mirror. Where as Blamps simply invert the mirror along the lines of an angelic choice. They are as they are because the penumbral focus is very precisely one person lving person wide, and they appear in a dark mirroring of life as undeath that consumes life directly because of this, also why they grow in strength with every feed/kill, they are true immortals in their own rite.
And flesh masks isn't shapeshifting, they're created separately from the body—elder Red Court vamps can hide from the sun in the shadow of their flesh masks, which they wouldn't be able to do if they were turning into something else.
Causing manifestation of a foreign body part that is not actually of the self(ergo the ability to hide in it's shadow) is actually quite the same as the transformatives done by grey, expand your concept of shapeshifting.
I'm stating that the transformation process of turning into a Red Court vampire isn't a gradual process; it's one that has a definable beginning and end. Half-vampires are the middle of that. Once they turn, their human self is destroyed and supplanted by the vampire. It's represented by their physical body changing. There is simply no way their human self could survive the stress of turning, aside from the implications of the vampire consuming it. Because they die, their soul remains intact. Again, when you see a vampire, "you aren't seeing your friend; you're seeing the thing that killed them."
Nope, Blood slaves are the end of the transformation process, the ability to hold onto your own will, ergo resisting this complete deevlolution into the thing you came to embody is their key to 'royalty'/position. Also how Mab is said to maintain any of who she is, Who you are going in is directly culpable in both regards, ergo Susan's continued love for her child so as to Sacrifice herself for her. Makes her mortal enough for me, as it does my Lawyer Mab
*also directly contradictory to woj on Blamps vs whites and reds. Blamps aren't what used to be human.