Fairday's Riddle: Branching Out...

Hello, Riddlers! Can you guess our theme? I like to find a good, artsy one and use it to decorate. ~ F

Part of the whole; consisting of the same. I'm useful, harmful, interesting—depending on your game. If you need a fire, I'll oxidize the air. Looking for protection? I'll swing at those who dare. Perhaps you're feeling fancy, and like natural decor, I can be artsy when placed rightly more.  

What am I? Stop by Friday for the answer.

I gave you a clue!

FEAR NOT THE UNEXPECTED