This is probably something addressed in the book but I can’t seem to find the answer. Hesitation is 10 - will. Does this decrease as Wil increases? Or, if you burn a character with B3 Wil is he always doomed to 7 hesitation?
I’ve always seen it played the former way, though a cursory scan of the Advancement and Steel sections didn’t turn up anything conclusive.
Hesitation, Reflexes, and Mortal Wound are all recalculated when your stats permanently change.
Note that these are stats that don’t, themselves, ever get tested. Because there are no tests they have no other way to advance.
Ah, yes, we have no desire to accrue challenging tests for MW. 
Wait, doesn’t wounds reduce your reflexes? scrambles for his books (and equipping armor)
yes, of course it does. But the context of the OP is talking about permanent changes based on increasing stats.
Good good, just been so long since we’ve had to use the fight mechanics. Mostly bloody versus in my weekly games.
Also, note that wounds immediately reduce Reflexes, instead of leading to a messy “recalculate your Reflexes based on your stats”.
Well, it effectively is just a short-circuiting of the full recalculation since (Reflexes - 1) is the same as ( (Speed - 1) + (Perception - 1) + (Agility - 1) ) / 3. But yeah, thinking about it as an immediate reduction in the final calculated Reflexes is easier (that’s definitely how I do it at the table for instance).