Re: for the fighting knife, straight or curved blade?
The Fairbairn Sykes "Commando" knife certainly has the bona fides, history and legacy to lay claim to being a true fighting (and killing) knife. And, all of the knives that you also mentioned can lay claim to the same; Kabar, Tanto, Bowie and Persian.
Now, at the risk of angering some, I would suggest that the other blades that you mentioned have slight to pronounced curves in their blades. Personally I would suggest that having curves in the blade helps with any slashing cuts as it tends to engage more of the edge, rather than the point, when cutting in that manner. Yet in spite of the curves, with the exception of the Persian all can be used to stab with no hindrance. Therefore, you see that I tend to be more of a "curves" fan, not much but just a little.
As to sharpening I would suggest you try a handheld sharpener such as an Ultimate Edge diamond type stick as the geometry of a knife such as the F/S changes dramatically as you reach the point and is hard to sharpen on a bench stone.
Hope this helps.
Ernest R. Emerson
Last edited by Ernest Emerson; 03-26-2010 at 16:17..