Weapon's elm haft troubled man wielding blade (12)

I believe the answer is:

flamethrower

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'weapon's' is the definition.
(flamethrower is a kind of weapon)

'elm haft troubled man wielding blade' is the wordplay.
'troubled' indicates anagramming the letters.
'man' becomes 'r' (abbreviation for rook, a chess piece or 'man').
'wielding blade' becomes 'ower' (I can't explain this - if you can you should believe this answer much more).
'elm'+'haft'='elmhaft'
'elmhaft' with letters rearranged gives 'flameth'.
'flameth'+'r'+'ower'='FLAMETHROWER'

Can you help me to learn more?

(Another definition for flamethrower that I've seen is " something of an incendiary issue".)

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