Method to Acquire - Visit the right house in the northeast on Chapter 9 and speak to him with Roy or Fir on Chapter 11.
Damage - He'll probably max strength at around level 10 Warrior. He deals massive damage to enemies, especially enemies with Lances or flying units.
Critical - Not so good. Unlike Garret, Gonzales and Geese who get critical bonuses as Berserkers, he just gets to use a Bow as a Warrior.
Speed - It's really bad. Thankfully, his Constitution is high enough that he won't be losing much speed if any holding a weapon.
Dodge - He averages a dodge of 48, which is HORRENDOUS. It can be bumped up to 63 with the weapon advantage, which is still nothing amazing. However, on Chapters with lots of Dragon Riders and Dragon Lords, it is a good idea to stick him on a Mountain or in the Forest for a dodge of 83.
Growth Rates
HP - 70%
Strength - 40%
Skill - 20%
Speed - 30%
Defense - 20%
Resistence - 5%
Luck - 20%
Average Level 20 Warrior Bartre
HP - 60
Strength - 29
Skill - 15
Speed - 15
Defense - 14
Resistence - 4
Luck - 18
Total - 155
Supports
Fir - 10/20/27 turns
Gonzales - 59/60/80 turns
Cath - 59/60/80 turns
Zeiss - 59/60/80 turns
Karel - 20/30/40 turns
Rating - 7.5/10. Unlike Ward and Lott, he's not frail when you get him. He will also tear up enemy units with his high strength and you can always fix his skill with a few secret books. His only problem is he doesn't have great gains. He's exceptional for a prepromoted unit and has good support options as well.