So far I've had missing meshes for Redguard Helm, Silver Flamberge, Imperial Kettle Helm, and Kettle Helm. If they outside on the ground they show up as yellow triangles with exclamation points or if I wear the helm my head is bald, so I know they are missing meshes I just don't which files I have to reinstall.

Oblivion.esm
Francesco's Leveled Creatures-Items Mod.esm
Francesco's Optional New Items Add-On.esm
Oscuro's_Oblivion_Overhaul.esm
Mart's Monster Mod.esm
FCOM_Convergence.esm
EnhancedWeather.esm
TNR ALL RACES FINAL.esp
TNR - ShiveringIsles.esp
Francesco's Optional Chance of Stronger Bosses.esp
Francesco's Optional Chance of Stronger Enemies.esp
Francesco's Optional Leveled Guards.esp
Francesco's Optional Chance of More Enemies.esp
FCOM_Francescos.esp
FCOM_FrancescosItemsAddOn.esp
FCOM_FrancescosNamedBosses.esp
DLCFrostcrag.esp
DLCSpellTomes.esp
DLCHorseArmor.esp
DLCOrrery.esp
DLCShiveringIsles.esp
Bob's Armory Oblivion.esp
FCOM_BobsArmory.esp
Oblivion WarCry EV.esp
FCOM_WarCry.esp
Oscuro's_Oblivion_Overhaul.esp
FCOM_Convergence.esp
FCOM_RealSwords.esp
FCOM_LessRats.esp
FCOM_HungersUnitySI.esp
FCOM_DiverseGuardUnity.esp
FCOM_BobsGuardUnity.esp
FCOM_Archery.esp
Knights.esp
FCOM_Knights.esp
Visually Realistic Lava.esp
QuietFeet.esp
ChaseCameraMod.esp
Bedrollsanyone.esp
EnhancedWeather.esp
EnhancedWeather - Darker Nights, 80.esp
Enhanced Vegetation [150%].esp
Enhanced Water v2.0 ND.esp
No Recharge.esp
SkipTutorialv2.esp
Streamline 3.1.esp
Bashed Patch, 0.esp

Get FormIDFinder and install it. You will be able to tell what mod the items are from using it and then you should be able to solve your problem.

It might be an issue with Bob's Armoury (I think those are things added by it). Do you have the BSA for the mod that you can get off the FCOM thread?

I installed FCOM recently. I noticed one installer installed the mesh files to a folder under data folder. Normally I would notice but installers are too automatic. Check if you have a data folder like data/data in there.