Female only (barring special class change situations). They're basically a more offensive / well balanced Lord.
Class: Soul Strike: Can hit ghosts, and ignores armor of everything else? Half armor? Not sure.
Mastery: Physical attack up (224.0% max)
Mastery: (3DS Only): Priest spells up (unknown max). You can simulate this in the PSP by giving them that one EX Skill that gives them healing bonuses?
Mastery: Lady of the Spear: They can equip spears as sub-weapons (dual wield)
Starting Class: B. They gain priest spells very slowly, but have good HP. However, if you want a neutral character with priest spells, this is your only option. (Outside of changing alignment.)
Ending Class: A. Dual Wielding spears is GREAT. And they get 9 casts of all priest spells! That's amazing!
No Class Change: A. There's an Innocent Spear that's really great. If you're going to use one Innocent Class, this is the one to use.
Lady of the Spear really increases their damage output, especially by the end of the game. Since they can stay in the rear they can be really, really amazing. And Gothic added a TON of spears.