But be contented when that fell arrest 1. Or the but may be taken as relating to some antecedent argument and discussions with the beloved, stemming from the original declaration of 71 No longer mourn for me when I am dead . Note the punctuation of Q, which does not put a colon after contented . It is followed here, apart from the removal of the comma at the end of the line. See SB p.261.n.1-2 for notes on alternative punctuation.
Death is personified as the official who carries out a court's decree.
But there is also more than a hint of the other meaning, the act of stopping something in its course. Hamlet uses the words before his death in the same sense as here. But be contented when that fell arrest etc . Without all bail shall carry me away, 2. Without all bail - this continues the legal terminology.