I got your PM, so I'll answer in here.
As you know, I recently made a Monster Hunter Tri (Wii) weapon editor and I still have my notes for that. http://www.romhacking.net/utilities/1627/
I used the debugger in Dolphin to find the weapon stat table in the iso file. Here is some of that info which may help you find what you're looking for in your Monster Hunter 3 Ultimate 3DS ROM. Keep in mind that Wii uses big endian, and I think that 3DS uses little endian.
Monster Hunter Tri (Wii) weapon stat table info for the Iron Lance. This is from the iso file (you can use a hex editor to view this):
0x16A57AA = Iron Lance Rarity value (changes it from Rare1, to Rare2, etc)
0x16A57AC = Iron Lance cost (4 bytes).
0x16A57B0 = Iron Lance Sharpness data (2 bytes).
0x16A57B2 = Iron Lance Attack/Damage value (2 bytes).
0x16A57B4 = Iron Lance Defense (Def +) value (1 byte).
0x16A57B5 = Iron Lance Affinity value (1 byte).
I haven't done much with 3DS games, so I'll get back to you when I've done a little research.