Olympian's sword (4)
I believe the answer is:
epee
'olympian's sword' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for epee that I've seen before include "Another fencing sword" , "Thin fencing sword" , "Foil for riposte" , "Use it to fence" , "Fencing sword, heavier than a foil" .)