So, I have two principle problems with this, but one of them I will actually solve by adding a new category to the mecha CS. 

The energy shield really is more utility than weapon, but I think I didn't give us enough options for what our mecha are armed with.  So I'm actually going to add in "Last Stand."  Er, I may come up with a better name for that.  This would be your ultimate ability, it should be a big deal, something that uses a lot of your mecha's resources all at once.  So your Feral Stalker would fit in there.  

The other thing is, I really feel like this should just be classified as a Light mecha.  The categories are there for a reason, different sized mecha are more suited to different roles. I think a machine with lighter weaponry, that is generally lankier, and uses stealth should be light, not medium.

Lastly, I just want to clarify, but I'm imagining that its hand attacks are using like bladed claws?