I recently acquired Umbra the sword, and i discovered that it is two-handed because of OOO, can anyone help me (a mod or a simple explanation of how to do it in the CS) get it back to a one-handed sword?

Do you want the vanilla Umbra sword or do you want OOO's Real Umbra replacer as a one-handed sword?

Open up the construction set. Click on the little folder icon in the top left. Double-click on Oscuro's Master File. Highlight Oscuro's Plugin File and then click the Set As Active File button. Click Okay.

When the mod has loaded into the CS expand the Items list in the Object Window box over on the left and then expand the Weapons list.

As Arkngt pointed out, there's two Umbras. Might as well change both, it'll just take seconds. Scroll down until you see DAClavicusUmbraSword and double-click that line. This brings up a box that displays all of the weapon's stats. In the "Type" drop-down box change "BladeTwoHand" to "BladeOne Hnad" and click Okay. Do the same for DAClavicusUmbraSwordOOO.

Click Save and exit.

What's Real Umbra replacer? All I wanta one handed Umbra with the stats it should have as one handed, if i'd change it in the CS would the stats be as they should?

Real Umbra Replacer is a mod that is merged into OOO - as mentioned in OOO's readme. It replaced Bethesda's sword model with a better-looking model. Oscuro's merged version also changes the sword's stats to conform to MOBS (as it does with every weapon in the game).

If you follow my instructions above you will be changing the sword from two-hand to one-hand only. Nothing else will be changed.

If you want to revert to Bethesda's original 1-Handed stats you will also need to change these stats to these vaulues:
Weight 45
Health 700
Reach 1.0
Value 4500
Speed 1.0
Damage 28

(For comparison, here are Oscuro's 2-Handed stats):
Weight 55
Health 23
Reach 1.1
Value 9600
Speed 0.7800
Damage 37

It's OMOBS rather than MOBS but, yes, giving the 1-H Umbra correct OMOBS stats is one issue. Vanilla stats will mean it's weaker than it should, but just giving it the same OMOBS stats as the 2H version will unbalance it in the other direction. Depends on how important one consider such things are I'd guess.

That change in CS will only switch animations of the weapon, and not the weapon's position on character's model, as this info is stored in weapon's nif file.

This will give you the original 1H Umbra if you load it after Oscuro's_Oblivion_Overhaul.esp. It's exactly the same sword as in the original game so no edited stats. Haven't tested it but it should work fine as it's just a simple override: http://www.4shared.com/file/FGzUB7lU/OOO_Vanilla_Umbra.html.

Well, it did gave me the original sword, only now it does 72 damage, and even with the 2H version it did only 45, do you know what caused this?

It's just vanilla stats so that must be something else interfering I guess. No idea what w/o seeing your load order. :shrug:

Also, you're welcome...

Yes, I was wondering if that was the case. Thanks.

Thanks man!
How do I put my load order in here from the mod manager?