A guy called EthanSilver has reverse-engineered the game (v1.203), in case you were interested in how it ticks:
Spellcards / Skills
Dummied spellcards List of skills and spellcards which exist in the game but aren't used anywhere.
Skill/spellcard data The function which sets up all spellcards and skills. Contains the name, description, max lv, and purchase/upgrade cost.
Spellcards formulas, (v1.1) A list of all spellcards' effects and formulas, extracted directly from the game. Does not include certain "unique" effects however.
Spellcard-specific code (Incomplete.) The mechanics behind some of the spellcards' more "unique" effects.
Passives and their effects The effects of the passive skills with unclear descriptions/unspecified numbers.
Characters
Passive stat boost setup code The function which sets up all characters' passive stat boosts.
Character and subclass modding Explains how to modify character stats and available skills, as well as the skills learnable through all subclasses. A hex editor, such as XVI32 or HxD, is required.
Enemies
JSON enemy dump (v2) A dump of every enemy's data in JSON format.
Enemy stat viewer
(JS, v2) (HTML, v1) Displays qazmlpok's enemy data in HTML format.
Enemy AI listing A list of all enemies' AI, extracted directly from the game.
Others
Hack: 3 commands for Remilia Gives Remilia a 3rd battle command (should be changed to suit your needs; new offsets for her skills are 06A338, 06A342, 06A34C).
Event Dump A (slightly simplified) list of all events in the game. Doubles as a list of in-game dialog too.
I figured putting this stuff in its own place would be for the best. It has pretty much taken over the
thread the discussions started in and is leaving little room for gameplay discussion. It will also be easier to maintain an up-to-date list of files and documents produced from the game's data.
The information in this thread is based on LoT2 English-Patched v1.203.