The 2nd page of the Active Help text under "Armoury Bonus" says:
The first sentence hasn't been true since late beta. The armoury bonus is a flat 50% as long as your current level is at least one lower than your highest class.Quote:
This bonus grows larger the greater the discrepancy between your current level and the level of your highest class. Use this to your advantage when deciding when and how to raise secondary classes.