[quote=@Senhara]
I have a question, for melee weapons, could I give my mech a Pilebunker?
[/quote]

I actually did have something similar to that already in mind for a default weapon card: It's called a Thermic Lance and it operates on a similar principle, using a two-stage warhead to pierce directly into armour in the same way. 

The weapon cards are meant to be archetypical, anyway: You can flavour them however you please with things like make, model, caliber, etc.

[quote=@Senhara]
Second edit, for my mech can I throw in L and R leg modifications and a few design quirks to explain some of the machine's properties?
[/quote]

Tell me what you had in mind and I can give you some better pointers