I'm not seeing how mass staredown really helps with AoOs. It makes enemies shaken, which, while useful, isn't that great a debuff in the grand scheme of things. Certainly not worth ten levels of samurai.
Please forgive the unsolicited advice, but it may be possible for us to build a character able to do what you want a bit better, and still be able to contribute to the party reasonably well (while sticking to your concept of a samurai). If you'd be willing to accept some advice, please tell us how far you're currently invested in the build (i.e. how much is your DM likely to let you change), and what sources are open to you?