Ibrahiim - your curved knife is a form of folding billhook - used mainly for pruning of fruit trees/bushes and grape vines. Known as a serpette in France, and a roncoletta in Italy (diminutive forms of serpe and roncola respectively) - it is found all over southern Europe and the Mediterranean area. I would guess yours in probably Italian in origin, possibly from the Maniago region.
see:
http://www.couteaux-jfl.com/serpettes.htm Sailors' knives tend to have a square blade, see:
http://www.linder.de/en/artikel/Kniv...Sailor’s_knife