All he's saying is that the "look" isn't quite there.
That Alucard's at 2x scale, whereas your Raziel towers over him. It'd be different if Raz was ten feet tall, but in-universe he's likely around 5'8 or so, even less considering his usual slightly hunched stance. The size you have him at now is closer to Dumah's height.
The complaint about the pixels is a little easier to explain. Without intending to give offense, it does kind of look like you drew the sprite with the square-block tool, rather than the typical pencil tool for spriting.
I understand firsthand (and then some) the immediate feeling of defensiveness when confronted with uzo's criticisms, but in this context I don't think there's a real need for it. Aside from saying the pixels look fucked up (which when compared to SotN's sprite style they kinda do), it's not like he outright insulted your work; he's just trying to figure out how you got it done.