It's not too bad to break the DLC apart but I actually haven't worked out the .pac file encryption yet so I wouldn't be able to modify the file sizes in the header if the .nbl contents were bigger than before.
Haven't looked at the stats yet but I've been investigating the naming conventions for the files, here's what I've got so far.
The files seem to be named with the following pattern
ITM{aa}{bbb}{cc}{d}.EDAT
aa – Sub-Type (list below)
bbb – unique id
cc – Type (01=weapons,08=visual units,09=costumes – with colour palette display,10=costumes,11=room items)
d – manufacturer (only for weapons, 0 otherwise) – 0=GRM, 1=Yohmei, 2=Tenora, 3=Kubara
aa
If cc = 01 (weapons)
01 - long sword
02 - knunkle
03 - spear
04 - double saber
05 - axe
06 – twin swords
07 - twin dagger
08 - twin claws
09 - single handed sword
10 - single claw
14 – rifle
15 – shotgun
16 – bow
17 – grenade launcher
18 – cannon
20 – handgun
21 – crossbow
23 – machine gun
24 - staff
25 - wand
26 – mag unit
28 - shield
If cc = 08 (visual units)
04 – always seems to be this
If cc = 09 (Costumes – with colour palette display)
06 – always seems to be this
If cc = 10 (Costumes)
06 – always seems to be this
If cc = 11 (Room Items)
05 – always seems to be this
itm{aa}{bbb}{cc}{d}.unr holds the related values for aa,bbb,cc and d internally so an existing DLC could possibly be updated with a new unique id and the files renamed - I'll have to try it. If it works it would allow a new DLC item to be produced that could then be distributed without the need to replace the original official DLC, the next step would be to update the stats and model (renaming the weapon and updating the description is easy)
Edit: Proof of concept, I created a test separate English version of ITM01015010.EDAT as ITM01255010.EDAT



I was able to import both versions, add them to my inventory and it didn't seem to fall over in battle
