Green’s Dictionary of Slang

soft-horned adj.

stupid.

1838		T. Haliburton Clockmaker II 139: You might have [...] bought it and failed, as some of our importin’ merchants sew up the soft-horned British.
1844		Essex Standard 30 Aug. 4/6: You might have traded with him and got it for half nothin’ as some of our importint [sic] merchants sew up the soft-horned British.
1856		Belfast News Letter (Antrim, N.I.) 28 Oct. 2/3: We think this is enough to prove to all sceptical and soft-horned Protestants that the Inquisition is no joke even in the year 1856.
1861		Elgin Courier (Scot.) 31 May 7/5: All fired gonies soft-horned pair, each will you lick? / You everlastin’ dolts, forbear!