Boon gave the standard Yoshinkan responses...this is a nice attack to shake up your shite...
Especially if a tanto is involved! There is a mawashi response that can lead to any number of throws, basically you block with the close hand and pivot, strike uke's face with the free hand, if they block, juji nage or mawashi (lead their blocking arm around and behind causing them to pivot away from you, nice balance break for kotegaishi or pretty much anything else you want to do.
Best,
Ron