Specially aboout his military arm.
When is not in service, he uses a Type 25c one, that is covered by fake fur, customized specially for the red fox. If you don´t look and specially hear very carefully, you never would notize that is not natural.
Marcos medics knows that put a mega strong arm in a non resistent body just will end in an HOSPITAL BED, so they suggested him to try a very resistent arm, more compatible with his foxy body and also a good shield if neccesary. This armor is just used for specific missions, because makes him lot slower but lot more resistent to enemy fire.

Hope this helps to understand more his weapons and stuff