@Jabra:
Not completely baseless, given Mr. 1's talk about Zoro cutting diamond next yada yada. I also can't imagine a better user of this fruit than a swordsmen.
Actually, if you think about it a Swordsman is possibly the worst person to give the Diamond fruit too. It hasn't been established whether or not Mihawk or other strong swordsmen can cut diamond, but assuming they can it makes the fruit kind of pointless. If the Blackbeard Pirates follow the traditional "like fights like" style of combat we've seen so far, Shiliew would be the one fighting all the high-class/expert Swordsmen in the New World. You're giving someone a Defense that's basically impervious to everybody BUT the most likely type of enemies that he would face.
Though if Mihawk can't cut Diamond, that all changes and it becomes incredibly smart again. I think Zoro's teacher once mentioned that being able to cut diamond is the mark of an expert swordsman though.
Also, a Zoro vs. Shiliew with Diamond Fruit fight feels a bit too similar to his fight with Mr. 1.