I suspect that most koryu sword arts taught a certain degree of "contingency" grappling for situations like you're describing. From the little I've seen, Kashima Shinryu has a lot of this type of thing. Takenouchi Ryu, which specialized in armored and armed grappling, would be another great place to look for more information, as would any of the other grappling-oriented schools such as Araki Ryu, Kiraku Ryu, etc. Jikishinkage Ryu has several kodachi kata that involve an element of grappling. Hope that helps.
David Sims
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