This is the large dorsal fin (and conveniently hiltlike finbone) from a gummi plesiosaur. There is a fine line between club and sword, and this thing is just sharp enough to be on the sword side.
(In-game plural: gummi swords)
|TOP 10 gummi sword collections|
6. whizdad - 6 | 7. agargan - 6 | 8. Stan Maskelyne - 6 | 9. Noskilz - 5 | 10. Sal the Rapacious - 5
Collection data courtesy of ePeterso2 and Jicken Wings