Green’s Dictionary of Slang

flashy blade n.

a dandy.

1719		in D’Urfey Pills to Purge Melancholy VI 104: In youth a nauseous flashy fop, in elder days a bore.
1806		G. Colman Yngr John Bull III ii: Its that flashy spark I saw crossing the courtyard.
1819		‘One of the Fancy’ Tom Crib’s Memorial to Congress 40: For though all know that flashy spark [etc.].
1820		Cobbett’s Wkly Political Register 29 Apr. 114/1: You know how a young flashy blade of a merchant feels and looks and is.
1826		Morn. Post (London) 2 Feb. 3/3: Two flashy-looking sparks [...] were yesterday brought up before the sitting magistrate.
1826		Liverpool Mercury 20 Jan. 6/1: I’m bright without — within I’m dark, / Like many a specious flashy spark / [...] / The stateliest dame, the coyest miss / Will clip with me but never kiss.
1889–90		(ref. to 1780s) Barrère & Leland Dict. of Sl., Jargon and Cant I 368/2: Flashy blade (old cant), a fellow who dresses smart (G. Parker).