Fellowship is defined as "your character's ability to interact with other creatures, to deceive, charm or befriend." This doesn't sound like it's a purely physical characteristic, yet there are several critical damage effects that permanently lowers fellowship, well only 6, and you could make a case for Rending - Head - Critical Damage 7 since it says you have trouble speaking without slurring your words after it. As luck would have it just one of my characters have personaly felt the full force of half of those. That was an void born adept with a starting fellowship of 25, so not very suited for social interaction to begin with, but I can just imagine what this would do to a Scum or Cleric (the heavily fellowship based careers).
Now since fellowship clearly is not just based on how you look, you should be able to repair these damages with reconstructive surgery, something that I feel could be suggested in the book, but even if you don't, 5 of those 6 should be able to be negated simply by not showing your face, or as Energy - Body - Critical Damage 8 would have it, the body. But even if you don't do that, how would a burned or scarred face diminish your ability to deceive someone? It's not like it would make i easier to read the face. I do think that you could require the master chirurgeon talent to be able to perform the surgeries, and maybe a number of successes depending on the severity of the damage.
Have any of you already used reconstructive surgery to fix this, or maybe removed the fellowship damage all together?