Primal Gladiator's Mail Waistguard is part of the transmog set Primal Gladiator's Ringmail Armor (Shaman only), which the Appearances collection lists in 2 versions. The other 16 pieces:
Items Numbered Next to Primal Gladiator's Mail Waistguard
Blizzard numbers items as they are created, so the named items next to ID 115941 (115936 to 115946) were usually added in the same batch as Primal Gladiator's Mail Waistguard: the same quest line, zone, vendor or reward set.