Well, here's a quick run-down of how much damage the pirate does, depending on your ATK:
(Pirate's stats are 180 HP, 430 ATK, 210 DEF. Player's DEF should be 80, so the pirate is doing 350 damage per hit.)
ATK 230 = Pirate gets 8 hits = 2800 damage
ATK 233 = Pirate gets 7 hits = 2550 damage
ATK 236 = Pirate gets 6 hits = 2200 damage
ATK 240 = Pirate gets 5 hits = 1850 damage
ATK 246 = Pirate gets 4 hits = 1500 damage
ATK 255 = Pirate gets 3 hits = 1150 damage
ATK 270 = Pirate gets 2 hits = 700 damage
I don't actually think it is possible to get ATK 255 or 270 before fighting the pirate unless you do use the invisibility potion to bypass him and come back later. But ATK 246 is certainly attainable. I'd suggest you do a thorough search for ATK gems in the first six Rules. If it helps you locate them, my ATK at the end of each Rule was:
Click here to view the secret text
×Rule 1: 22 (short sword)
Rule 2: 26
Rule 3: 64
Rule 4: 92
Rule 5: 143
Rule 6: 249
____________________________
50th Skywatcher