Ha yes I remember noticing that some time ago.
Also something I forgot to reply to last time.
Now, I'm wondering about one interaction--rocket punch keeps all a weapon's properties. Drill Rocket Punch also ignores half nat AC, armour to AC, and DR. The weapon is Power and Rending. It might just ignore all of them if those stack.
That question had already come up with Anomander's character and my ruling was that when you combine two "ignore 1/2" effects then it will ignore 3/4, so we'll be keep running with that unless somebody has a strong objection.