Should the Science Skill be used to repair Energy weapons and Power Armor?
AKAIK only the Enclave was capable of making Power armor, and very few in the games could repair them. (In FO1 the PC makes a very minor repair to get a suit that didn't pass inspection).
I would not want Science to be used for repairing the armors by itself, but rather would have it be a secondary check to see if the PC even knows what is wrong with the device to begin with. Just because the arm seems dead (for example), does not mean that anything is wrong with the arm. :shrug:
To repair PA, perhaps the PC should have a 90+ in both Science
and Repair.
*(And actually IMO that should be the minimum to attempt it with any chance at all... But unfortunately the rules no longer follow the series in FO3, so it would just have to be the two 90's for repairing the suit.

)
Alright, I never said it didn't make sense. I said that it would simply force you to spend your skill points in two sets rather than one, if you wish to repair your weapons frequently.
You then said that not replacing the repair skill for energy weapons is oversimplification? How does being made waste more skill points to be able to use something that is essential in combat "deeper"?
There is no "waste" of skills in a good RPG; only what you PC is good at or not. :shrug:
If they are not good at it, then you are not supposed to succeed at it often (or in FO3's case at all, I guess).
If an RPG offered a skill Bullwhips, and there was only one bullwhip in the game, and they were low damage and useless on armored opponents... Its still not a waste to use skill points on it if that's the player's choice; If that player's character is to be good with whips. Not being good with them is just that. :shrug: And being good with them means your character can use it professionally. (Ideally that skill should afford a few options in a few places... Options to play Indiana. :chaos:)
In an RPG, no single PC should grant access to all actions or all outcomes in the game ~It negates and devalues any aspect of "role" in the Role-Playing Game.
** In context... If you must cripple other skills to achieve high enough skill in Science & Repair, to be able to work on Power Armor, then that's the price of it; or its not an option to your PC. :shrug:
I should mention that I am of the opinion that certain extremely esoteric disciplines should be off limits the the adventuring PC, and only the domain of certain specialist NPCs; and their special equipment. It is very realistic to presume that Power Armor (and just about any so-called high-tech device) cannot
be repaired without specialized tools and authentic replacement parts ~even if you did know what was wrong with it; but actually those tools should be required just to figure out what the problems might be.
In the case field repairs where you have two (or more) identical damages devices (energy weapons in this case), I don't think you would need an above average Science skill to just swap parts; You would need it to be able to substitute parts though... (Even so, the need for specialty tools for something like Power Armor should be respected IMO... You can't even fix some parts on a bicycle without custom wrenches designed for the job).