"In durance vile" is a very old way of saying "in jail." Imprisoned.
Although "durance" is today considered an archaic term and its roots are even older, its linguistic cousins, words such as "endure," "duration," "durable" and even "during," are staples of modern English. All these words hark back to the Latin "durus," which originally meant "hard" but also had the extended meaning of "lasting," and "durance," which first appeared in English in the 15th century, originally meant "duration" or "length of existence." The "imprisonment" sense of "durance" developed in the 16th century and referred to the length of the sentence a prisoner had to serve.
The "vile" in "durance vile" is our modern word, meaning "low, despicable, contemptible, depraved" and similar unpleasant things. "Vile" comes from the Latin "vilem," which meant "cheap, of low value or quality," and this was one of its original meanings when it entered English around 1290.
Source Columns Posted 04-26-01
NOUN: Confinement or restraint by force; imprisonment: “There should be a durance vile for justices who use an argument as weak as the one the majority used” (George F. Will).
durance. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Student or Learner