Waved sword I discarded (10)
I believe the answer is:
brandished
'waved' is the definition.
('brandish' can be a synonym of 'wave')
'sword i discarded' is the wordplay.
'sword' becomes 'brand' ('brand' can be a synonym of 'sword').
'discarded' becomes 'shed' (I've seen this before).
'brand'+'i'+'shed'='BRANDISHED'
(Other definitions for brandished that I've seen before include "Waved" , "Displayed" .)