With that T-shaped blade back, it looks like a Khyber knife, from the Afghanistan/Persia area. Usually with a straight blade, the T-back was to reinforce the blade to pierce chain mail armor. A guy who really knows these things is Bernard Levine, a knife expert and appraiser. This is his site--he does charge for appraisals, but he will also give you a free preliminary opinion whether a knife is worth enough to justify the expense.


http://pweb.netcom.com/~brlevine/appr-k.htm