Now that’s perfect!!! Nero’s right arm vs his rival’s left leg!
Now the rival’s gonna need weapons of his/her/their own!
Nero has a motorcycle customized sword & a modified revolver added alongside his demon arm.
For the rival having a demon arm, what melee & ranged weapon would you have it possess?
If a sword, perhaps anything other than European or Asian… how about African like a khopesh from Egypt?
If not a sword, perhaps a polearm?
As for guns, I could imagine an SMG? Or magnum?