The rest of the boss equips.

Unless party lets you solo, it's impossible to fight boss alone. At least 3 members needed. I wanted to solo it too, but i guess not =[

EDIT: From what I know/experienced, the boss has 180,000 HP and hits 250 avg both magic and physical.

Astaroth (Boss)
Level: 32
HP: 180,000
MP: 500
EXP: 5250
Avoid: 15
Speed: 30
Knockback: 800
Magic Attack: 180
Magic Defense: 150
Physical Attack: 180 (259 ~ 275)
Physical Defense: 150

For the record~

Edit: oops, sources were wrong~