if you use the bulkhead sheers with your servo arm what penetration do you use? 6 from the sheers? 10 from the servo arm? or 16 from both? You add the strength bonus from the servo arm so you are already doing 4d10+19.
My call would be 10 pen as with most things in this game you take the higher of the 2 scores......but a difference of 4 is not something I would complain about.
Same goes for the drill. Also why have something (like the drill) be power and unwieldy? Doesn't that defeat the purpose? if you can't parry with it, then it can't use it's destroy weapons ability right?
In the end, I can have 3 attacks at 4d10+19 6-10 pen rending.....which is pretty crazy melee from a tank-bot.