That one girl on Mothership Zeta the one you see at the beggining(sorry I dont know her name)
A merchant named Haley in Point Lookout, (DLC) can repair almost anything to max CND.
You need to purchase and install the Point Lookout.
Located Haley's Hardware Store, Enter and speak to him, exit and re-enter. Repeat until his repair skill reaches 100.
You may need to FT somewhere else if going in and out of the store does not increase his skill.
It should not take you more than 10 minutes to raise his skill to 100.
Do not, attempt (inserting a better armor) or actually pickpocket his unique repair suit. EVER
His skill has never resetted for me, no matter how often I FT there. (300 times or more I'd say) I have never waited for longer than 73 hours at any point inside PL. And he is still selling the Tri-beam Laser Rifle I sold him weeks ago, (2 years in game time) and even though the rest of his inventory restocks, the tri-beam somehow remains there... Buying it and selling it back did not make it go away. (I hate this weapon, which is why I bring them to PL so it cannot be used against me. Hardly anyone other than the merchants have MFC in PL.)
Note: Some Headwraps cannot be repaired. (DR 1, WG 0, VAL 0, Effect(s) None) Also items with extremely high HP such as the Wintertized T-51b, cannot be repaired unless its CND falls below 99%. Same goes for any items with abnormally high HP. Gauss Rifle from the Operation Anchorage Simulation can only be repaired after 5,000 shots or more. Or it's VAL goes down to 498.
Basically, he needs to be able to charge you for the repair of the weapon (bringing other items in poor condition does not work) He needs to at least be able to charge 1 cap or more for every item you want him to repair. Try using the Heavy Incinerator; aim at your feet and shoot. Repeat process. (find a room, and sleep when your health goes down.)
If you don't have Point Lookout, you could have Somar repair them, given that your repair skill is at 100, and you have not completed the quest... You could also use Alien Epoxy to repair them.
It is possible to use a scavenger but this is most time consuming and requires careful and precise adjustment of his/her skill. It does require you to Mez and make him/her put on a skill increasing clothes, Vault 101 Utility, Red Racer, Robco, Dad's Shirt etc, and they must incease the skill, SPECIAL boosts will not affect the scavenger's repair skill. The effect is not permanent. Location; Penn. Street, North inside Freedom Street Station. It can only be done if the Scavenger is still wearing the Merchant's outfit DR1. Mez, open inventory, exit, repeat process. The same way you would increase your companions' stats. The effect stacks unless the item increasing the skill is unequipped. (Note: Scavengers can remain in one spot but it would be a different scavenger when his/her inventory resets.) I've personally never tried this, so... Buy and install Point Lookout... Do not raise the skill over 102.
If it's the Alien Blaster, hand it into Casdin, (Do not give him any ammo) leave area, come back and shoot his weapon with a Gauss Rifle or a Victory Rifle. run up to him, open his inventory, retrieve the weapon, and croutch, activate stealth boy then FT away. Note: His weapon is the Ripper and is very difficult to hit without hurting him; if you do miss or even partially scratch his armor obviously turns him hostile. And the Outcasts will never forgive you; in which case; you could have simply shot him and retrieved the weapon.
Invest in Crazy Wolfgang, and reverse-pickpocket a Worksmen's Coverall from Point Lookout. That's quite close to 100%. (might as well just use Haley but still.)
Yourself provided you have 100 repair and more copies of the weapon.