05/16/08: X_Loto made an important discovery regarding in-battle status blocks. Sweetness! Details below.
05/18/08: More work from Mr. Loto. It's getting there!
05/28/08: Thanks again to X_Loto there's more info in here.
06/12/08: Waylay got his lazy ass around to doing something. Yeah, he fixed ONE grammatical mistake that probably went completely unnoticed anyway. Woo.
01/06/09: Lawl. In the above update note I had left a 'y' out of 'anyway.' Ironic, really, and now corrected.

Slots are relative--ie, leaving the first "slot" open on the status screen will not skip "slot1" in battle--
the character in "slot2" (or 3, etc.) on the status screen will then be "slot1" in battle.

Each section of in-battle stats is 0x204 (516) bytes long. This is an attempt to decode those bytes.

I had suspected, and X_Loto has confirmed via debugger, that stat blocks start earlier than initially stated here. Rather than beginning at 1D824, the ACTUAL stat blocks follow:

1D800/1DA04/1DC08/1DE0C/1E010 - PCs
1E214/1E418/1E61C/1E820/1EA24 - ??
1EC28/1EE2C/1F030/1F234/1F438 - Monsters
1F63C/1F840/1FA44/1FC48/1FE4C - ?? <-- Interestingly, x_loto's findings indicate this last block is not actually used (the first 3 blocks of 204hx5 are cleared by a routine which left the 4th block as it was.)

00--23: ???
24--25: Current HP
26--27: ???
28--29: Base MaxHP (Corresponds with status byte 04--05, says x_loto)
2A--2B: ???
2C--2D: Max HP (Maybe this factors in RaySword? That's Waylay's present hypothesis.)
2E--2F: ???
30--31: Current LP
32--33: Max LP
34--35: Current WP
36--37: Max WP
38--39: Current JP
3A--3B: Max JP
3C: Race/Gender byte (Corresponds to status byte 16, says mr. loto)
3D: Corresponds to status byte A1 (credit to x_loto)
3E--49: ???
4A--4B: Status (see below)
4C--5B: ???
5C: Total Str
5D: Total Qui
5E: Total Int
5F: Total Wil
60: Total Psy
61: Total Vit
62: Total Cha
63: ???
64: Base Str
65: Base Qui
66: Base Int
67: Base Wil
68: Base Psy
69: Base Vit
6A: Base Cha
6B: ???
6C: Str mod (magic)
6D: Qui mod (magic)
6E: Int mod (magic)
6F: Wil mod (magic)
70: Psy mod (magic)
71: Vit mod (magic)
72: Cha mod (magic)
73: ???
74: Str mod (equipment)
75: Qui mod (equipment)
76: Int mod (equipment)
77: Wil mod (equipment)
78: Psy mod (equipment)
79: Vit mod (equipment)
7A: Cha mod (equipment)
7B--7C: ??? Seems 58 might have something to do with VictoryRune, went to 0D.
7D: Something to do with LightSword, Shield, and the like, it seems. Also modified by equipment.
7E: Equipment weight.
7F: ???
80-8F: Equipped Abilities
90-E1: ???
B2-B9: Equipment
BA: RaySword hidden slot (see below)
BB: LightSword hidden slot (see below)
BC-D9: ???
DA-E1: Defense values (see below)
E2: 05/20/08: This actually appears to be the internal value for what monster the creature is--while changing it won't cause graphics or names to change for the enemy, it will, for example, register as a different creature when a Mystic absorbs it; it does, however, change the name on the 'monster absorb' list at the end of a battle.
    05/28/08 Also, x_loto discerned that for characters this is the CharID#. (Corresponds to status byte 00)
E3: Sprite (for characters--different for monsters? Thanks to x_loto for this) (Corresponds to status byte 01)
E4--E9: ???
EA--EB: Character's Battle Counter (x_loto)
EC--ED: Corresponds to status bytes 9E--9F (x_loto once again~)
EF--F1: ???
F2--141: Corresponds exactly to bytes 38-87 of character status blocks. (Thanks to x_loto for this! He also realized that 13A--141 do NOT actually affect byte 90 of the character status block, contrary to prior opinion.)
F2--131: I know I'm repeating here, but these are the bit-toggle values for known skills/abilities. x_loto pointed this out. ^^
131--141: Correspond directly to status bytes 78--87; deals with Monster Form, Monster BaseHP, and Mystic Absorbs, although there are still 10d (0A) bytes unconfirmed. (credit to x_loto)
142--163: ???
164--165: Something to do with monster form--checks to see if Monster bit is set in Race/Gender, along with byte 1BA. (credit to x_loto)
166--167: ???
168--169: Last tech selected in battle. (Thanks to x_loto! Man's on fire tonight~)
  168: Which menu command is on:
    00--09: Equipment slots 1-10 (9 and 10 are theoretically the 'hidden' equipment slots at BA and BB)
    0D: Monster skills
    0E: Fists
    0F: Magic
    10: Mec skills
    If an invalid menu is force-fed it just defaults to the next higher valid menu.
   169: Command's position in menu.
16A: Corresponds to status byte 17 (more of x_loto's detective work ^^)
16B: Magick Gifts! Corresponds to status byte 15. (credit to x_loto, and shame on me for not seeing that sooner. :P)
16C: Is set to F0. (x_loto: why? I dunno) (Waylay: I concur o0)
16D--17B: ???
17C--185: 5 2-byte values copied directly from status bytes 88--91 (more of x_loto's work..all were 00 00)
186--18B: ???
18C--193: Monster absorbable skills
194--19B: Copied directly from status bytes 30--37 (thanks to x_loto for this--I'm sure we'll figure out what they're for eventually. :P)
19C--1B9:
1BA: Something to do with Monster form, along with bytes 164--165. (credit to x_loto)
1BB--204: ???

Status bit information:
1: Stasis?
2: Infinity--Magician Arcane effect?
   Does nothing if given to a character.
4: Sparkle--VMAX effect
8: Sparkle--SoulRune effect
10: Sparkle--Awakening effect
20: Blind
40: Stone
80: Venom
0100: Angry
0200: Charm
0400: Mess (Red)
0800: Mess (Yellow)
1000: Mess (Blue)
2000: Sleep
4000: Palsy
8000: Flat--Faint?
      Still alive, if HP>0

The RaySword/LightSword hidden slots work for any weapon you put there manually;
it's just that game code puts the appropriate weapon there when AlkaiserChange or LightSword is active.

Defense values:
DA: Slashing
DB: Blunt
DC: Piercing
DD: Fire
DE: Ice
DF: Electric
E0: Force/Light/Sonic
E1: Status