"Kill it, kill it, kill it" doesn't mean you are helpless, which is what you seem to be implying. Nowhere in the rules does it even suggest that you no longer get to roll defense if you're in a frenzy or berserk state. The only time you don't get to roll defense is when you are unaware of the attack (surprise attack, blinded, etc.).
Now if you are going to house rule things like that, it would have been a good idea to list that at the beginning, so I would know stuff like that.
And even if you were house ruling that, the spirit is the one actually in control of my body at the moment, and it is not frenzied.
Hell, even a ganger tripped out on K-10 still gets to roll basic defense, under the rules. Being driven into a killing frenzy doesn't mean you are suddenly take every hit that comes your way. It means you're always attacking. RAW, you still get your basic defenses.