Isn't it possible that Nightblood was based off of a Shardblade AND made with a dead Shardblade? If Vasher had visited Roshar before and somehow saw or heard of how Shardblades used to be alive and brought back a dead one, isn't it possible they were trying to restore the Shardblade to its alive state by awakening? Nightblood being the end result (an awakened dead Shardblade with the intent of restoring it to its life, but not really realizing what that life looked like).