I've tested this out a bit and its pretty clear what this does. It improves everything on automaton and it also boosts abilities/spells/WS potentecy. So it'll be a good idea to use this before your automaton WSs or does that huge 3 ice manuver MB. The boost is something like 25% to everything, i'm just giving you an idea on how much overdrive improves your automaton.
Currently 50 pup, and i've used this 2 hour a couple times and yes it pretty much is useless. Honestly i dont see any difference in what it does. But i was thinking maybe its something like this... If your current Melee/Range/Magic isn't alrdy capped, possibly the PUP's 2 hour makes it so it caps for the remainder of the 2 hour. Then again ... why even bother still be pretty useless :P. Just a thought and like i said have no idea what it does, and i don't think SE does either. LOL!
Ok I am a lvl 33 PUP/NIN. I rarely use 2hrs abilities because my main is a 45 RDM and right now RDM 2hr is not that good except for mass healing if there is no whm in pt and we are in trouble. Anyway I was pting outside norg and got a link halfway thru a fight and I took the link on and used my 2hr. I did not see any differance in my pups hits or magic. Currently using the RDM frame. I am hopeing this gets better at later lvls. At this time it seems very useless. Would love to hear from a high lvl pup that has used this.
Basicaly, it makes your Automaton as good as he can get for that level, maybe a bit better? Idk, tahts what i've gathered from teh description up top..