Freeblade Rapier and Unstoppable

Another pass on trying to come up with wording for an ability that's essentially rendering a creature "stunproof":

I'm not sure really whether we really need an "unstoppable" keyword and even what the actual value of the ability is. If this set has detain, clearly it's going to be good against white and blue. There will be red effects that prevent blocking. And there will be black and red creatures that cannot block, so you could even use it on them to block with (though I'm not sure why you would). The wording here also overrules defender, so I could even make a strong defender creature or two it could interact with.