Curved weapon — I'm covering it in something left after battle (8)
I believe the answer is:
scimitar
'something left after battle' is the definition.
I can't judge whether this definition defines the answer.
'curved weapon i'm covering it in' is the wordplay.
'curved weapon' becomes 'scar' (I can't explain this - if you can you should give a lot more credence to this answer).
'covering' is a charade indicator (letters next to each other) (in a down clue, some letters go on top of others).
'in' is an insertion indicator.
'im'+'it'='imit'
'scar' going around 'imit' is 'SCIMITAR'.
Can you help me to learn more?
(Other definitions for scimitar that I've seen before include "one that is very sharp" , "Steel" , "Type of sword with curved blade" , "I'm racist, owning an oriental sword" , "Curved oriental sabre" .)