Personally, I am a huge metal fan...When it comes to Black metal, I love that too. But only when done properly. Just because you`re in a Black metal band, that doesn`t mean you must write "Black metal lyrics" if all metal bands did that, then they would all make practically the same songs, and things would get boring.
I know that the kind of metal in question is associated with an image of blood and gore, but honestly...who wants to hear a song about blood? or even more relevant, who wants to write a song about blood.
I dont think I am a alone when I say that I believe songs should have substance and meaning. If blood has something to do with that meaning, well then thats great, but a song about blood is just stupid.
Maybe try drawing inspirasion from situations etc.