Hey,
thank you for your feedback! 
We have already an item checker in arena, which is preventing using corupted items in arena.
I can only quote, what a dev has written:
So, it’s just a display issue at the moment.
Beside of that, we are still banning people, who are cheating. So, if you see anyone who is cheating. Just make a screenshot and upload it here.
About root/hacking: The devs are working on it.