Authenticity guaranteed. 
True "attic find" - uncleaned, untouched, unaltered example.
Antique silver mounted arab jambia dagger.  
Yemen or saidi arabia, circa 19th - early 20th century. 
Precious grip material.
Hand forged blade. 
Silver mounted h0rn grip decorated with 3 worn silver coins and silver nails.
No scabbard (sheath).
One piece h0rn grip (carved from domestic animal cattle h0rn, mentioned to comply with ebay policy). 
Cattle is a large domestic farm animal kept for their milk or meat. This animal is not threatened or endangered or protected by cites, the endangered species act, or any other state, federal, or international laws. It is legal to sell this item and this listing follows ebay rules.
   size:
About 11 11/16 in. (29.7 cm) long (straight line).   
Blade is about 7 3/8 in. (19.7 cm) long.
  condition: 
Original vintage condition with expected handling marks, honest wear and charming indication of age.   
Blade is covered with even brown untouched patina, should clean up nicely. 
Heavy wear to silver coins on the grip.
 Fine quality antique example.