My very first attempt at a modification for NW was to first build all the SRD items by the books. While it was interesting, it was annoying as hell to do, and eventually created a generally worthless stack of UTI files nobody seemed to want, including me. What we ended up doing is transitioning to script-created item system where item properties, including custom new ones, or "fixed" ones where they differed in game from those in the SRD, would be added to an item on creation via scripts. That went fine, and I think you can get similar script packages on the vault already, right down to visual effects, which cover most of the needs you might have from the SRD. One of the drawbacks to the NW engine is that it was not set up to properly handle on-crit stuff, and that might cause you a great headache trying to actually fit SRD descriptions.
I've since then added so many new item properties, including varieties of ones already in the game, that UTI no longer is a logical choice, as they would no longer fit across servers. A great majority of the work I put into the unreleased 4E project relied on a replacement function for DetermineCombatRound(). Inside, that function required that certain item properties, or even spell-created item properties, be on a weapon, but not actually modify a stat sheet. This allowed me to create my own combat system, which for the most part cloned the basics of 4th edition mechanics, except in a way that worked with my custom token system, where characters learn traits with which they create their own attacks, allowing them to recreate any low to mid-range attack from the 4th edition books for all races and classes. High level spells and attacks no longer fit the mold, since at that point about 20% of the spells were no longer checked for consistency from lower level powers, which was a real turn-off for me regarding 4th edition as a tabletop system. By creating this new combat system, including all the many needed new item properties, I was able to create my own on-crit scripts and solve the issue without requiring external programs.
Based on that 4e mod engine, I was able to bring an old program I had written in visual basics over to the land of 2da. That old program was modeled off the original "dnd treasure generator" which was geared for automatic 2nd edition treasure generation at the click of a button. It used files similar to NW's 2da files, pointing to either another file in each reference, or returning a name. Mine was released as the 3rd edition equivalent before even 3.5 came out on the shelves. It was wonderful, and we eventually added files for all of our custom items, or items we found in other games at the time, including everquest item properties. Converting it over to use with 2da was fairly simple for 4th edition, but mostly because their item property setup is lame.
If anybody is interested, here's a list of all the current new item properties I added in the 4e mod
- ability check bonus (ability) (value)
- ability check penalty (ability) (value)
- bypass resistance less than (spell descriptor) (value)
- crit extra damage treated as damage type (damage type)
- crit extra damage die size increase (die size)
- crit extra damage die size increase vs alignment group (alignment descriptor non-specific) (die size)
- crit extra damage die size increase vs condition (condition) (die size)
- crit extra damage die size increase vs race (race descriptor) (die size)
- defense bonus vs descriptor (descriptor) (value)
- defense penalty vs descriptor (descriptor) (value)
- extra damage with spell descriptor (descriptor) (value)
- implement designation (implement type)
- on crit run script (script reference)
- on encounter end run script (script reference)
- on encounter start run script (script reference)
- on hit run script (script)
- on struct run script (script)
- reroll damage dice while value equals 1 [take the higher value of two rolls]
- reroll dice on ability check (ability)
- reroll dice on attack (attack type)
- reroll dice on damage (damage type)
- reroll dice on skill (skill)
- reroll dice penalty varieties for those listed above [take the lowest value of two rolls]
- resist vs race (race) (value)
- skill check bonus/penalty (skill) (value)
- suppress crit extra damage
- vorpal 4e [add die when die is maxed]
- vulnerability (descriptor) (value)
- weapon damage type override (damage type) [all damage dealt by weapon is of selected type]
I'm not even sure at this point I got all the needs for 4e or not, but this must have been pretty close, as I put about a year into just this part.