It was, the blessing got replaced by Yune. So either it has two blessings, or just the one. >_>
And you can't steal equip'd weapons in FE10. In fact, it's impossible to remove Ragnell from Ike's items list. Has a nice lock on it, one of two weapons you can use with a lock on it (the other being Amiti). I'm however, not fully sure how that would translate over into this.
And then there is the question of how on earth is Sonic going to be able to steal the weapon? He has to lose his speed in order to be able to do so. Ike's not weak at all, Sonic won't be able to just run by and pluck it out of his hands. He can't grab it by the blade of obvious reasons (super speed + edge = lol gg you just killed yourself), and the handle doesn't stick very far out. He has very little surface area he can grab. He's going to need two hands to even attempt doing so, and the only places he could grab are on each side of the blade. Again, no super speed while doing this due to the awkward angle he would have to grab the handle.
And EVEN if he took the sword SOMEHOW: Ike's still invincible from all of Sonic's attacks. >_> Or he could pull out another sword/axe.