Your trainer wants you to use your skills to prove that you are ready to face the many dangers that exist in the world.
'I am ready to help you learn how to become a more effective Mariner. As you gain levels, more skills will be available for you to unleash upon your foes.
'Use your skill Thrust against a Training Dummy. You will find that certain skills move your Balance either towards the Fore or to the Aft, which will have various effects upon your combat ability!'
Use your skill Thrust on the training dummy nearby.
Barton Halifax, the Mariner Trainer, is in Archet, west of the training grounds.
Now that you have successfully used your skill, you should return to your trainer and tell him of your success.