So based on process of elimination, from Gowther's commandment being passed down to Fraudlin, and piety given to Zeldris, and Drole and Gloxina filling the missing slots that Meliodas caused, that leaves Grayroad as the only commandment not present during the Ten Commandments flashback.
Does that mean, Meliodas' old commandment was pacifism? That would make sense, since pacifism would be the opposite of his sin: wrath.
But that leaves an even bigger question, Meliodas is clearly seen killing a Goddess in Estarossa's flashback. Plus his ruthlessness back then is clearly stated. Wouldn't him killing someone trigger the age curse of the commandment?