Each mark requires its own test.
The Mark of the Seeker is reserved for those who pass the Trial of the Seeker. You must be above level 35 to qualify. To take this test visit Master Dufner of the Town of Giran.
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 Sagittarius is reserved for those who pass the Test of the Sagittarius. You must be above level 39 to qualify. To take this test visit Guild President Bernard at the Hunters Village.