Each mark requires its own trial.
The Mark of the Challenger is reserved for those who pass the Trial of the Challenger. You must be above level 35 to qualify. To take this test you must visit Kash of the Town of Dion.
The Mark of Life is reserved for those who pass the Testimony of Life. You must be above level 37 to qualify. To take this test visit Master Cardien of the Town of Dion.
And last, the Mark of the Duelist is reserved for those who pass the Test of the Duelist. You must be above level 39 to qualify. To take this test you must meet Duelist Kaien of the Town of Oren.