I did a search and couldn't really find any pertinent information, so i was wondering what are the restrictions on the different types of armor (if any) on the classes?
For instance... a high level archer can/cannot wear heavy armor?
Anyone can wear anything. But it's generally the best idea, to wear armor that you have masteries for, unless a certain armor set has a bonus that you'd really like to have.
The only real restriction, is armor grade (NG, D, C, B, A, S).
Using an armor that you do not have a mastery for has basically two effects.
1) You do not receive a Pdef bonus. (All)
2) Your casting speed and MP Regen is reduced. - (Mages)
#1 is more important for Light Armor (Only) users, while #2 is of importance to Mystics. All Mystic Classes recieve by default a skill that increases MP recovery and Casting speed while wearing robes. So if you wear a light or heavy armor without the mastery you suddenly seem to be casting at 1/2 speed and MP regen is noticably slower.