Method to Acquire - He starts with you on Chapter 8.
Damage - Astol isn't as good of a fighter as Chad is, but he's way better then Cath.
Critical - Not so special, thieves don't get any critical boost and unless you give him a Killing Edge, his critical won't be very high.
Speed - Like most thieves, Astol is very quick. He won't max speed at as low as level as Cath will, but he may max it. His speed gain isn't as good as Chad or Cath's though.
Dodge - Astol's dodge is alright, it's never as high as Cath's, but it isn't TOO bad. He has an average of 53 dodge as a level 20 Thief, which isn't too great.
Growth Rates
HP - 90%
Strength - 35%
Skill - 40%
Speed - 50%
Defense - 20%
Resistence - 20%
Luck - ?15%
Average Level 20 Thief Astol
HP - 34
Strength - 11
Skill - 12
Speed - 20
Defense - 9
Resistence - 5
Luck - 13
Total - 104
Supports
Lilina - 15/30/40 turns
Bors - 30/30/40 turns
Barth - 25/30/40 turns
Wendy - 30/30/40 turns
Igrene - 50/60/80 turns
Rating - 8.6/10. Astol is the lazy man's thief. If you don't level up Chad, you should use Astol who isn't as good but is better then Cath.