Can someone please explain to me the appeal of Invisible Blade? Feinting is weaksauce and HARD to do (Glibness doesn't help; enemy adds full BAB to its sense motive check), and with eratta even as a free action is still only once/round. The AC bonus requires no armor to be worn at all and caps at +5 only after five levels in the subpar class and making yourself slightly more MAD (multiple ability dependent) than normal by bumping your int up to 20. All offensive abilities gained only work with daggers, which is also a bummer when you need bludgeoning, or... when you want to use flasks.
I made an Invisible Blade several years ago because the fluff sounded cool. After a few levels of it, I got sick of the gratuitous amounts of suck, went into Master Thrower DESPITE intending to be primarily melee, picked up genuinely good class features like free trip on every hit, and actually felt competent all of a sudden.
And yet, CO still seems to like this guy. What am I missing that an Invisible Blade brings to the table that say...a Ring of Blink (well affordable by the time you hit IB 5) can't do for you, better?