Once you reach the level of a hegemon (level 20), the gear you pick will be essential to surviving the higher level areas. A piece of gear is determined to be hegemony based on the amount of armor it contributes to that particular slot. There are old pieces of gear as well as new that will constitute hegemony gear. Normally, it is safe to assume that if it's the best armor for that slot, or maybe even second best then it will probably be counted as hegemony. The drawback to kitting yourself out in all the best gear is that you will notice that monsters and NPCs lower than level 20 will reward much less XP. This is directly related to the number of hegemony pieces you are wearing, so be forewarned. This is to promote the idea that you should be fighting harder monsters, since wearing all the best gear renders lesser monster fights much less experience-worthy.