Blade made from copper salts being forged (7)
I believe the answer is:
cutlass
'blade' is the definition.
(cutlass is a kind of blade)
'copper salts being forged' is the wordplay.
'copper' becomes 'cu' (chemical symbol).
'being forged' is an anagram indicator.
'salts' anagrammed gives 'tlass'.
'cu'+'tlass'='CUTLASS'
'made from' acts as a link.
(Other definitions for cutlass that I've seen before include "Pirate's sword" , "Short, heavy curved sword" , "Short broad sword" , "Old sailor's weapon" , "could hurt one, in the main" .)