The Headmaster Title – Secret Title
The Headmaster / Headmistress Title is a character-bound hidden title and is obtained by completing an Archaeology quest chain in Legion. The quest chain is relatively short and starts off with the quest https://www.wowhead.com/quest=41183/academic-exploration in Dalaran.
https://www.wowhead.com/npc=103482/taethelan-bloodwatcher hands out the next quest and can be found in Azsuna, east from the Illidari Strand.
/way Azsuna 47.5, 42.5
Upon completing the quest chain, you will be awarded with a https://www.wowhead.com/item=131744.
Using this item in the Hall of Arcane Learning will transport you to a time-warped version of the room where you can do more mini-games such as more rune drawing and picture fighting. Here you will also find https://www.wowhead.com/npc=112111/elya-azuremoon who you may duel after completing all the activities (although some speculate that you can simply walk up to her and duel her).
Challenge her to a duel, and if you defeat her, your character (and any others who were in a party with you) will obtain the Headmaster/Headmistress title for their character.