If you have any means of allocating and sending pics of good quality...please do. If it has a fair amount of rust and damage to it, it will be much harder to identify. Pics of the tang and tip and overall profile would be important. If the blade is in relatively good condition and has a hamon visible (hamon is a "temper line" as some call it, on a well polished blade it will be a milky or luminous white) or hada (forge welding grain patterns), try to get pics of it also. Do not remove rust from the tang, do not rub the blade with sandpaper or go near it with a buffer until someone has taken a fair look at it. If it has metal fittings, do not try to polish them or modify them in any way, again until they have been given at least a once-over.
Online "appraisals" are difficult to accomplish, but in a lot of cases you can get at least some degree of information regarding your piece if the information and pics are reasonably detailed. Let me know if you need to email the pics or if you can post them or whatever method if possible.
Good luck,
Shinryû.