I currently have a level 21 spellsword that I have been leveling with a 1/1/1 ratio for magicka, health, and stamina. I am starting to think however that this may be a bad idea as higher level spells can get pricey. I do have a mod that increases destruction magic damage with your level to help it stay feasible even at higher levels, but not as insanely powerful as melee when you abuse crafting and start doing over 1k damage a swing lol.

I tend to use destruction spells until the enemy closes on me, and then finish them off with my sword. I also find that my one handed and destruction magic skills level up at about the same pace, so it seems I am about 50/50 magic to melee.

As it currently stands, if I kept up my current ratio I would end up with 370 magicka, 370 health, and 360 Stamina. The magicka level is my biggest concern, the health and stamina however I am not so concerned with. I play on adept difficulty and will be maxing my armor and magic resistance so that will help with health, and I usually don't need to do a heck of a lot of power attacks since I soften enemies up with magic first.

Can anyone recommend a good ratio to use for leveling from here on out. I currently have 170 magicka, 170 health, and 160 stamina at level 21 to give you an idea where I am starting off from.

I'm not really an expert on Mage builds, as my current Mage is the only one I've ever played. But IMO it seems that you may be not putting enough perks into magicka. On my Mage I pour my points into magicka and keep my distance. As for your spellsword, I think maybe a 2/1/1 in magicka, health, and stamina ought to suffice.

hmmm, so that would leave me with 500 magicka, and 300 health and stamina if I adjusted my leveling to reach that end ratio. I wonder if that would be enough health to safely face some of the new dragons dawnguard adds at high levels when combined with 80% damage reduction and 85% resistance to magicka on adept difficulty.