Actually I have a few questions..
I'm throwing mythical weapons in the db just to play around and get to know the db and the tables a little better. I'm having a couple issues however.
1. Where in the database can I find the icons? I see appearance and can grab them properly but I'm not quite sure where to find an icon for an item (like when you see it in your inventory).
2. How are weapons with damage over 255 handled? The guardian epic has a max damage of 308, yet the damage_high fields only allow an integer up to 255. I thought maybe the 3 damage_high fields would be a sum or something, but it looks like it's only taking the last two fields (damage_low3 and damage_high3).
3. Do item effects work? I can't seem to figure them out.

I cannot answer much to how Items work since I have not played with them myself - but someone else can.
What I will mention, just as an FYI, do not waste time creating Items for the emulator as we will be parsing that data from live collects soon enough. It just hasn't been a priority yet and is still likely a few months away.
But if you are doing it merely for your own knowledge, please share once you are enlightened.

Yep! I've only created just a few to understand the tables and what is linked to what and such. I'd figure later down the road we'll be able to reference this post.

Just another note regarding items...
On live with the last update they reitemized the entire 1-59 level group to bring it into line with the RoK newbie and high end items.
Because of this, every item from 1 to 59 is now different, so either we are going to have to start parsing items from scratch, or have inconsistent data since some will be before the change and some after.
In addition to this, tradeskill created items are being reitemized in LU 48, with items from 60-69 along with items with procs being reitemized in the "near future" (proc items were skipped since it is impossible to write a script that can weigh the "goodness" of items with procs).

Aye, while there are 12,000+ items listed in our DB, I think all of it is old and outdated, and maybe doesn't really work anyway. The parser is not equipped currently to handle items (anymore) but LE is going to sort that out soon enough.
My question is, when you say "latest update", do you mean the Live Update that recently passed, and not the ROK expansion? If so, this might mean all our item collections are junk. Because anything we collect from here out will not match? If I am reading you right.

When I say "the latest update" I mean the Live Update that happened with client 5016L going out.