So my character is a melee/magic user, who focuses on melee a little bit more. I'm dunmer who was born under the sign that gives me 10 points to willpower and endurance, can't remember what it was called. My specialty is combat, and my favorite two attributes are strength and endurance. My 7 major skills are alteration, armorer, blade, block, destruction, heavy armor, and restoration. I was thinking about switching my birthsign to the Warrior and then switch strength with willpower as my favorite attribute to balance what I loss.

Any suggestions on what I should change? Race change, birthsign change, anything?

And I'm only using the FCOM mod if that changes anything.

Battle Mage is the name.

Being as you're using FCOM I don't think you have to be as perfect with your skill choices as you would in vanilla.

10 bonus to willpower and endurance will be great, especially the endurance boost. If you intend to be a melee caster then endurance is pretty good, so the more you have earlier on the better.

You could change strength to intelligence if you think you'll be casting more. Dark Elves start with 40 strength and 40 intelligence IIRC, so either will be fine.

Being as you have Heavy Armour as a major, you could drop armourer for something else. Both contribute to the endurance bonus, so you can drop one for something else if you wish. Maybe get Illusion to help out with those big packs (calm and frenzy).

My Battlemage build is in my signature.

I would choose Endurance and Intelligence for your favored attributes (I had specific role playing purposes for choosing Endurance and Strength)

Your choice of birthsign is good. I also had a specific role playing purpose for choosing "The Atronach".

With Heavy Armor, do you plan on using full suits of armor? Do you plan on using shields, or 2-handed weapons? If you plan on using full suits of armor, you might not need Alteration, as you'll get the full amount of armor bonus and won't need Shield spells (unless you're selecting Alteration for other uses?)

However, I do believe Alteration and Shield spells are great if you're like me... not using shields (I use 2-handed Claymores), and I don't wear helms (I wear hoods for RP purposes). Thus, I can't max out my armor rating with just armor.

Outside of that, I think your skill choices are fine, and I'd never knock a racial choice. I like going against the grain sometimes, and making Redguard mages, or Breton tanks.

If you're looking for efficiency tho, Dark Elves are a good mix between melee and magic.

I plan on using a sword and a shield, but if I come across a 2 handed sword that's a lot better than the sword I'm currently using, I'm definitely gonna switch it. And I also do plan on using full suits of armor. I chose alteration because it's a habit of mine. I always chose it back in Morrowind since it was one of the most useful spell classes in the game, but I forget that it's different in Oblivion, like it there's no levitation in Oblivion.

If you're gonna primarily be sword and board, and use full suits of armor, then Alteration might not be the most useful skill (again: at least for Shield spells - I keep mentioning Shield spells because that's really my only use for Alteration), but that's not to say it'd be worthless.

Armor degrades quickly, and you may not always be able to repair, even if you do take Armorer as a major (until you get to a certain level, you can't repair enchanted armor, for instance), so Shield spells can come in handy in those circumstances.

Outside of Shield spells, there is still always Feather spells, Unlock spells, which are very useful.

I prioritize character design over efficiency... for instance, I took Block as a major, even though I use claymores, because even without a shield, blocking is a huge part of my character vision. So if Alteration is a school that you like, I would say take it. You're not going to get armor rating 85 suits of armor right off the bat anyways