Hi!
I need some help on making a Mage who can use a sword if his mana is low.
I will mark the things i will certainly use with * (Star).
I'm thinking about:

Race: Breton or Dunmer
Specialization: Magic*
Attributes: Intelligence* / Strength or Willpower or Luck
Birthsign: The Atronach*
Skills:
Long Blade*
Destruction*
Alteration*
Illusion*
Light Armor or Heavy Armor

Breton gets more Magicka but he is low on Endurance and Agility (He has a huge amount of Magicka so he gets into sword fight less often than Dunmer but when he is out of Magicka he will have a hard time at close combat)
Dunmer is better at fighting but his Magicka is low (He will get into close combat faster because he has lower Magicka, but he is better in sword fights than Breton)

Also i don't know if i should use Block / Armorer with Heavy Armor and Long Blade or just use Light Armor and Long Blade (nothing else)?
I think the Light Armor + Long Blade would be the best choice, because i want to be mainly a Mage but he is cursed with the The Atronach sign, he needs some kind of protection / weapon when he is out of Magicka.
What do you guys think?

Why not axe? A mage can summon a bound axe very early on. Sorkvild the Raven uses an axe; it's not anti lore and it has many advantages: the bound axe has the highest base damage in the game (80), it's weightless (big deal for a weak mage) it gives a 10 point skill boost for better chance to hit, and it has the highest per use factor of any weapon so the skill raises 10% faster than other weapons.

Well, i don't really want to summon weapons. I want to use weapons when my Magicka is low and if i summon a weapon my Magicka will be low sooner, so that's a dead end for me

Well, this is true for a cast summons but it's easy and cheap to make an enchantment. For example, a silver axe (not too heavy and good enough for low level critters) enchanted with bound battleaxe would be a good solution.

The Atronach sign allows any race to become good spell casters. there are red guard mages around. red guards are good with long blades.

if you like to have enchanted equipment, ebony allows more enchantments than glass.

the game allows unlimited training so you can train the skills to get the stat build you want.

if you do a custom build, just use the first ten skills to make a statement, to define your PC, your alto ego.

Care to make the game a bit harder for you? Instead of Breton, which makes the game easier, try being an Altmer. You get the most Magika but have the most weakness to it. Antronach sort of helps if it's a magika cast at you because you can absorb it. Well if you are a Breton that is a great combination, but I find it too easy so I had to restart and be an Altmer.

Also remember most characters at the end of the game, are the same. So while you say Bretons are low on Endurance in the begining of the game, at the end, they are the same as everyone else, so I wouldn't worry about that.

I wouldn't worry about armour. Since mages really don't use armour, I would have it as a tertiary skill. I forget what they call it. Not major, minor, but none at all I guess. Yes you will svck at it, but Your mage should only have armour only for certian situations, unless you are a Battlemage then you would be using Heavy. Unless you are a Spellsword type character I guess. But will you really be wearing armour all the time?

I would use block if you want. I am sort of like you. I use magika, but seem to run out alot, so I end up using my sword alot. So my character is like a Jedi. Great with the force, or magika, and great with the long sword as well.

I really don't like Altmers, the only two Race i would play as are the Dunmer and the Breton (Don't get me wrong i don't say bad things about Altmers, they are just not my style )
Well, i always prefered Dunmer when my friend showed me Oblivion years ago, but the Breton are so tempting for my playstyle, the only downside of him are his Attributes (Dunmer is more agile for swordfights, but no bonus Magicka).. Oh and the biggest reason i didn't play as Breton in Oblivion, because of the high willpower bonus as i don't need willpower if i'm an Atronach, so the Dunmer was the winner for me in that game (i like to play Morrowind and Oblivion with the Same race and with almost the same skills), but you are totally right, at the end they are almost the same.

I wanted Light or Heavy Armor for when i get into close combat, but you are right this time too: Mages doesn't need armor specialization, i was just afraid of being killed when i'm in a sword fight but i guess the armor doesn't make that much difference

Altmers are not weak oO. They have the highest mana pool in the game, and heavy boosts to magic skills, just like bretons do. And they have more life than bretons. Properly equipped, they are more powerful.

And, everyone needs armor. Heavy armor. Its the one where the most enchantments are. One endgame heavy shield has more enchantment slots than all the best light armor combined. That having said, no matter the chosen armor prof, in early game i walk around in light armor, everything else is just too heavy. that and you get a very good full set of light armor pretty early in the game too, especially if on PC.(probably a bug)

Just remember you are only weaker in the begining of the game. Towards late begining game to middle game you can have thoses low stats up to where you want them. I wouldn't worry about Stats too much.

I think Dunmer are the way to go. I loved the look and feel of them in the game. I did change to Altmer when I wanted something harder. I think you can't go wrong with Dunmer or Breton. Good choices.