Greetings, old EO player and hacker here to drop some hints and infos!
To Begin with i see ya'll lack best equipment ids, so here they are
33:Dragon Blade
64:Sunbade
105:Trident
143:Danda-Chakra
180:Ameno Habakiri
225:Ameno Makagoyumi
265:Ukonvasara
302:Yatagarasu
348:Origin Tablet
558:Knight Armor
559:Royal Byrnie
560:Carbide Armor
596:Berserker Leather
597:Calico Sailor
598:Interceptor
599:Vajarana Vest
600:Kokopelli Vest
629:Dark Vest
630:Beast Chain
631:Orion Epaulets
632:Chajin Jinbaori
655:CathBhar
684:Dark Gauntlets
751:Ocean Shield
And yes they are purely the best stat-wise as forges are completely customizable, so yes, you can have anything with 8 empty slots. The amount of forge slots is right after the id in the game's memory and the pointer for the forge slot attachment is right after.
Forge Ids
1:Atk
2:Hit
3:Blind
4:Sleep
5:Str
6:Tec
7:Vit
8:Agi
9:Luck
A:Poison
B:Confuse
C:Paralyze
d:Stun
e:Plague
f:Curse
10:Head Bind
11:Arm Bind
12:Leg Bid
13:Crit
14:Fire
15:Ice
16:Volt
17:Stone
18:Death
19:(Blank Box)
1a:Hp
1b:Tp
1c:Slash
1d:Bash
1e:Pierce
1f:Spd
20:Lim
Fun fact: Atk forge works on any piece, including armors. So you can have 32 (8x4) atk slots for massive dmg boost, but game is still "balanced".
Chars with subclass can have both Class Skills at the same time. If you learn some of the topmost skills in the skilltree for your subclass ad the bottom ones for your main (just learn all of em) you can see the address in the middle, the one that stays 00.