Baronet's or 'little barons' are those rich knights, typically holding several manors, who can afford to knight all their children, not just the heirs.
Tahnarism is the ability to manipulate a portion of the Anti-Principle (the "force" present in Bukrai) to accomplish tasks. It is an attempt to introduce necromantic magic into Hârn that does not rely on the Morgathian Church and its pre-occupation with death.