Diamonds aren't as hard as people think, many can break easily just from being dropped a few feet off the floor. In smaller sizes, they are purer in crystal formation, and harder to break while sharper. Personally, A Guyver VS Twilight fight is not much different from a Zoanoid fight considering twilight monsters are probably weaker than Gregoles.... and Gregoles can tear apart tanks. ...however, this does bring to me a blissful dream of a twilight massacre since I so dearly hate that franchise (though I do respect that they actually removed the silly non canon vampire weaknesses.