Can we please stop pretending there is any reason to be an assassin rogue before level 12 and skipping straight to assassin II? The Assassin I enhancement is pretty worthless still. Please just ditch the stupid poisons; nobody bothers to use them, they barely work, and they're lame on top of all that.
Is there any chance we could get something mildly useful? For instance, nobody uses daggers. They're pretty terrible as melee weapons (exceeded only by the mighty light hammer). Remove the whole poison idea and give assassin 1 rogues x3 crits with daggers. It would give us a medium threat range weapon (that we didn't need to burn a feat we can't afford to lose - EWP: khopesh) with a decent multiplier that is kept in check by the low base damage vs other exotic or martial choices (khopesh, dwarven axe, warhammer, heavy pick, etc.) After all, nobody hears assassin and thinks "i bet he's using a khopesh". The dagger should be the weapon of choice for a stealthy killer, not a 3 foot long hooked sword.
This would make assassin 1 a great deal more attractive in that it isn't just spending 2/3's of your level 6 AP's for an extra backstab die and a confirm critical bonus. the acrobat and mechanic lines both have very useful and tangible reasons to take the first tier, make it so for assassins and bring a little flavor to the viable weapon selection in the game in the process.