Jackleg

[Jonathon Green]

Jackleg: seems to to find its ultimate source in the UK-wide 18C/19C dialect
_jack-a-legs_, a large, single-bladed clasp knife, usu. with a broad, square
blade. Thence seen as the type of knife a slapdash or unskilled caprenter
might use rather than more sophisticated tools and appears in US in mid-19C
as the simple 'unskilled', with alternates _jakeleg_ and _jack-legged_. Noun
form deals with various incompetent, unskilled or unprincipled professionals
or workers, esp. the jackleg preacher (although he can be simply an
itinerant).

_Jake brakes_ are beyond me, but there might, given _jakeleg_ be a link.

Jonathon Green