Axes hit higher but less precisely: i.e. you can do 40to 90% of maximum damage most of the times you hit. Swords hit consistently the same damage. Bows require 2 hands, i.e., no shields.

Chains is what FFXII calls when you kill the same type of foe in sequence, .i.e. keepe killing wolves on Eastersand and you get a chain going. The higher the chain the better the loot the wolves drop, plus your party gets random healing and good status changes. Kill any other kind of fiend and you break the chain

EDIT: What he said