If you’ve got hold of someone’s blood, it is for spellcasting purposes basically as though they’re standing right next to you, no matter how far away they are. They can’t hide from you, even behind wards, because you essentially have an in, because you have something that on a fundamental level represents their life. Which means that it’s very easy to get around someone’s protections if you’ve got their blood, not to mention that you can do a number of other necromantic things with it (blood transfusions in this world are both more effective [to the recipient] and more deadly [to the giver] than you’d expect).
Yes, replacing limbs (which does have to be done in-situ) is an example of one of the more benign uses; it’s not exactly painless - you feel the new nerves coming in, after all - but it’s a lot less painful than having the limb removed in the first place.
Shapeshifting in this universe is hard but possible, and that’s another example of fleshshaping.
Cross-breeding otherwise incompatible animals was popular for a while (many of the ‘monstrous’ animals in existence such as chimeras are the direct result of fleshshaping). As is simply sculpting some sort of half-living monstrosity bent on gluttony and destruction.
And there’s the Flesh Dragons. Did I have Serpent drop a hint about the Flesh Dragons? Dragons used to not be real. Used to.