Skill assessments are used to roughly gauge what level your at in a skill.
The best example is all weapons and armor require a certain skill to use to their full potential. By learning your skill assessment you will be able to better understand how well you can use a weapon or wear armor.
Note: Items may have custom skill or other requirements to use, so even if they say the assessment is in your range you still may not beable to use that item untill the unique requirements are met, which could be from class, guild, or even level.
To assess your skills just travel to your class hall and find a trainer or training room. Training rooms assess your standard skills, you may read the sign in the room to learn more details.
Trainers allow you to assess your class skills, if you are a fighter or monk you will spar skill with your trainer, if you are a mage you can use the standard assess skill, if you are a cleric you can ask your priest to judge skill, and finally if you are a rogue you can ask your trainer to evaluate skill.
Skill levels from lowest to highest:
novice, greenhorn, fledgling, amateur, tenderfoot, apprentice, capable, practiced, learned, knowledgeable, accomplished, savvy, proficient, adroit, apt, adept, high adept, expert, professional, savant, and master.
14:28, Shadowday, Kantki 16, 166 AD.