TR, the Free Dictionary's citation for this one is Webster's Unabridged Dictionary from 1913. Alan tends not to accept words from this source unless they can also be found elsewhere.
As for this word being common, I would say not, unless you speak Latin or Italian. A couple of death metal bands have used this word in their lyrics, but somehow I don't picture you as a death metal fan, ensiform.
I have found another current usage of revocate, other than in death metal lyrics, thanks to my friend Google. In the Singapore military reserves, the soldiers apparently use this term to refer to changing their MOS (military occupation specialty) such as cook, driver, police, rifleman, interpreter, corpsman, etc., judging by some bulletin board discussions.