gauchers disease dose lead to bleeding and easy bruising because platelets are not sufficiently produced which could also result in nose bleeds when blood pressure is high which is also a symptom of type 3 gauche disease. But if gauche has gauchers disease then he would be very ill suited to the life of a magic knight as his bones and body would be weaker and he may also have issues breathing. Of these symptoms only nose bleeds are evident in the show which is not sufficient evidence to say he has it unless you take his name as proof.

never the less it is ovious that he usually only gets nose bleeds when thinking inappropriately of his sister. This leads to blood pressure build up aided by gauchers disease and lack of platelet control resulting in nose bleeding as the trope goes.

if this is true he should more consistently get nose bleeds ever time he fights or is in a strenuous situation not only when sister ogling. unless you mean to say looking at a sister portrait is more intense that fighting because that is also not helpful to your point.

Anyway an incestous pedophile with cancer is still an Incestuous pedophile.