If you miss the kickblade you can't unlock the weapon (spoilers?)

[Yostage]

I missed the kickblade on my first pass though. Then I fought the mirror trainer fight where (according to the faq) you're supposed to unlock the triple weapon. Instead, I found the kickblade. Then I flew to where the kickblade is found, and again I received the kickblade. Now it seems like I can't actually unlock the super weapon.