@Boxer_Joe: I am not so familiar with Diablo. But I am extremely knowledgeable in Kekkaishi.
Shichirou can manipulate wind at his will and can cut buildings with ease. His winds are more powerful than Ichirou (who cut Masamori's Zekkai).
Kaguru is hypersonic+ if he cuts those who have regeneration abilities, they will be slower on healing then bleed to death. Kaguro can also adapt his blades so they can cut his opponent. He was able to cut through Quazi Zekkai.
Also Kekkaishi is my favorite manga ^_^
Diavolo/King Crimson's ability is probably one of the most-discussed JoJo powers, solely because it's somewhat confusing. Essentially, he erases segments of time. The beginning and end of an action will still occur, but the middle won't. There's a comic out there that explained it, but I can't find it. Essentially, someone shoots a gun at Diavolo, the bullet pierces him, and continues on its way, but King Crimson erases the moment when the bullet hits Diavolo, so the firing occurs, and the bullet traveling behind Diavolo still occurs, but the section where the bullet travels, hits D and exits his body doesn't happen anymore. I think that's a good way of explaining it.