Repair switch blade (6)
I believe the answer is:
rapier
'blade' is the definition.
(I know that rapier is a type of blade)
'repair switch' is the wordplay.
'switch' indicates an anagram.
'repair' anagrammed gives 'RAPIER'.
(Other definitions for rapier that I've seen before include "A thin double-edged sword" , "Thin sharp sword" , "Thrusting weapon" , "fencing equipment" , "Light sword" .)