Wiktionary lists conscion as a verb, with the inflections conscioning and conscioned. On the other hand the OED lists conscioned as an obsolete adjective, and does not have conscion at all. Other dictionaries know nothing of any of these words.
Three of the four usage examples cited by Wiktionary are using conscioned. The other uses conscioning.
It seems conscionable and unconscionable are derived from conscions, an archaic form of conscience.
Usage examples of conscion, conscioning and conscioned are all very thin on the ground. I'm going to go with the OED and accept conscioned as a rare word.