All of this is true, and all of it is tangential to my point: it is possible to conceive of a character that is able to condemn wickedness, even in themselves, without themselves being able to do good. Miko was able to condemn wickedness in others without being able to do good herself. Redcloak is able to condemn wickedness in himself and yet is unable to bring himself to do good, and he reached that point earlier in the strip than V did. The question is, can V go farther than Redcloak? I don't see a reason, beyond wishful thinking, to believe that she can.
Of course, some folks believe Redcloak's on a redemption arc as well, so maybe the board just has really lax standards.
Yes. If she doesn't have the right to decide who dies, she doesn't get the right to decide who lives either. Of course, she cannot ever have such perfect certain knowledge. What's more, that is an assumption you're making, not one backed up by the comic. Of the dragons we saw murdered, only a few of them were even interacting with other creatures in or near their own homes, let alone "despoiling and destroying" other people's.