Green’s Dictionary of Slang

blunt n.1

[? Fr. blond, yellow, using as in other sl. terms the colour of the coin to denote its name; or f. SE blunt, referring to the edge of unmilled coins, or, least feasibly, from Mr John Blunt, chief architect of the South Sea Bubble financial scandal of 1720]

[18C–1910s] money, esp. cash in hand; thus blunty, wealthy; unblunted, impoverished.

In compounds

blunt-finder (n.) [SE finder]

[mid-19C] a money-lender.

blunt ken (n.) [ken n.1 (1)]

[mid-19C] (US Und.) a bank.

blunt magazine (n.) [SE magazine, a warehouse]

[early–mid-19C] a bank.

In phrases

smart blunt (n.) [SE smart, to feel pain]

[mid-19C] (UK Und.) forfeit money.