That person was likely trying to desynth this. If this person was using a Lightning crystal, thats what likely happened. Other than that there is no recipe involving this item that I know of.
I tried synthing this last ngiht for guild item, only to find I lacked the skill to do it ;_;
based on lvl difference for attempted synths Im guess this synth to be ~ lvl 45 for smithing. since I have confirmed you can attempt a synth that is 15lvl different (even tho you will fail) and since I have a lvl 25 smithing, 25+15 = 40, so its above that, and the lvl for darksteel is ~45 so Id say thats a good basis for it.