We now know what Sword of Body and Mind does! Check out our Scars of Mirrodin Spoilers page to see!
A Spanish vendor website revealed a content listing for the From the Vault: Relics product scheduled for release later this year. Among it was the nugget that the unknown card from Scars of Mirrodin which will be included in From the Vault: Relics is "Sword of Body and Mind."
Unfortunately there is no art or card text to go along with it, only the name. It seems quite likely that this will be a further continuation of the cycle begun by the Mirrodin artifacts: Sword of Fire and Ice & Sword of Light and Shadow.