TV series example of the word

The Big Bang Theory Season 3, Episode 15
And I abandoned my goal to master Tuvan throat singing.

Game of Thrones Season 1, Episode 10
But my master got sick of me, so... here I am.

Game of Thrones Season 3, Episode 5
I'm Master of Coin. Saving money is important.

Game of Thrones Season 5, Episode 5
Yes. I'm sorry, master.

Game of Thrones Season 4, Episode 6
So, does this mean I am a master of something now?