@derpster Actually, Freida pointed out in P1 that a devouring child being sickly pre-draining is normal - she was as well - and the abnormal part is Myne still being sick post-draining.
Thing is, there are four events we know of that could have caused mana hardening:
The devouring attack at the start of the story The devouring attack after Effa burned the Mokkan The devouring attack at the end of P1V2 The poisoning in P3V5Now, that last one is after Ferdinand's examination of Rozemyne, so while it probably did make the clumps worse, one (or more) of the other three have to have caused them in the first place.
And since all three of them are pre-draining... There has been no point in Myne/Rozemyne's life when she was not either a)suffering from untreated devouring or b)full of semi-crystallised mana (and for P1V1 and P1V2, she might have been suffering from both). So we can't really say that Myne's body is just inherently sickly - no-one's ever seen what she's like without mana issues holding her back.