Save the Mark
In archery when an archer shot well it was customary to cry out “God save the mark!” —i.e. prevent anyone coming after to hit the same mark and displace my arrow. Ironically it is said to a novice whose arrow is nowhere.
So (in Othello, i. 1) Iago says he was “his Moorship's ancient; bless the mark!” expressive of derision and contempt.
In like manner (in The Merchant of Venice, ii. 2), Launcelot Gobbo says his master [Shylock] is a kind of devil, “God bless the mark!”
So (in The Ring and the Book) Browning says:
Deny myself [to] pleasure you, The sacred and superior. Save the mark!
The Observer (Oct. 26, 1894) speaks of “the comic operas (save the mark!) that have lately been before us.” An ejaculation of derision and contempt.
And Mr. Chamberlain (in his speech, September 5th, 1894) says:
“The policy of this government, which calls itself (God save the mark!) an English government ...”
Sometimes it refers simply to the perverted natural order of things, as “travelling by night and resting (save the mark!) by day.” (U. S. Magazine, October, 1894.)
And sometimes it is an ejaculated prayer to avert the ill omen of an observation, as (in Romeo and Juliet) where the nurse says:
“I saw the wonud, I saw it with mine eyes (God save the mark!) upon his manly breast.”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894