It's not above the one power- it's a different energy that works on different rules.
It doesn't really have a good equivalent in the cosmere- there's no magic in the universe that isn't investiture. Emberdark
But at least this, I don't think would matter. We'll say that "evil" is its intent, and as far as we've read, nightblood corrupts and changes all investiture, regardless of its shardic intent. I don't see why it would be different here.