According to the Dark Side Compendium, the Diamond Sword is to be awarded to "Members of the Brotherhood who have shown consistent loyalty...". I can think of no one more loyal the Dark Brotherhood than Exar Kit. This loyalty was tested in September of this year when the Dark Brotherhood was left without a site.
When I finished the code, I still needed somewhere to put it. Exy generously allowed us to host our website from his personal account for almost three months. Even more, he dealt with my persistent complaints about the server, the site, all the while working on fixing some of them.
I can think of no one more loyal to the Dark Brotherhood than Exar Kit. I know I speak for the entire EHDB when I say, "Thank You".