I have recently aquired 3 old kukris which were my Grandads which he bought in India during the war. Two are about 15 inches long and the third about 3 foot. There are no markings i can find other than some etched decoration on the blade. The sheaths are rotten due to age and i guess poor storage but the knives themselves are reasonably sharp. Any advice on how i should treat them and are they worth anything?