friend claimed to find Unobtanium sword

Hello,

Looking for some advice I recently started a server with 3 of my other friends i didn’t join the server as it was late and had one of my friends set it up before anyone got on (working late) within 30ish minutes of him on the server alone he claimed he found an Unobtanium sword. he claims that he got it from killing a wandering trader/a graveyard-he has two different stories. i am just wondering if this is even possible as chest loot or drop loot. I will check the logs when i get home from work to see if there is any funny business. Note we do use /op for teleporting and what not but not spawning in things. any help would be great. EDIT:this is all the mods 10