Read for basic math on weapons stamina use http://www.gamesas.com/index.php?/topic/1279078-2419-armor-6399-damage-using-smithing-alchemy-enchanting-only-33-perks-329k-backstabs-post-3/page__view__findpost__p__19432824
If you want a fair math here then (still this is so biast in favour of meele 1vs1):
Basic sword 21 dmg with perk 42, dual sword power attack 126 dmg (21x2x2x1,5) a hit
Destro lighting storm master level 112.5 dmg with 47 mana usage per second.
We skip the realistic values of health:stamina of meele and magica of mage and
go with the bogust 500 stamina and 500 mana values.
we go with 4 dual power attacks in favour of meele ( 72x2x0.75=108 stamina per power attack )
500 stamina gives us 4 dual power attacks that gives us 126dmg x 4 = 504 dmg per stamina bar
500 mana gives us 10 seconds of spell attack that gives 112.5 dmg x 10 = 11125 dmg per mana bar
Conclusion for non-mage race: 504 meele dmg << 1125 destro dmgnormal attacks take 65 mili-second to swing (altough Im not sure this works in an INT value, yes the animtion might be faster but is the dmg really too) one sword so we`re doing a constant 65 dmg per second.
spell dmg does 112.5 dmg per second but only for 10 seconds.
Conclusion for any mage race: 65 meele DPS <<< 112.5 destro DPS There is the penalty of mana running out after 10 seconds but we are fighting one oponent and we are gonna kill him anyway if hes 1k health,
This dosnt take into account the value of disintegrate that kills an enemy that has less than 20% health. ( if enemy has 1k hp then he dies instantly if he falls below 200 hp, bonus of 200hp less dmg to deal per enemy )
Doesnt take into value racial bonus of 50 magica, with it the mana bar dmg would be 1237 dmg per mana bar.
This conclusion dosnt take into account +magica gear (to be fair, really

) and makes the mage naked while the meele build uses armor to not get 1 hit kill in close range combat
If we want to be a bit more fair then 500 stamina gives us 4 dual power attacks that gives us 126dmg x 4 = 504 dmg per stamina bar
550 mana gives us 10 seconds of spell attack that gives 112.5 dmg x 11 = 1237 dmg per mana bar
Conclusion for mage race: 504 meele dmg << 1237 destro dmgIf target has 1k health then we need only (1000/126*0.65) 5 seconds to kill it but need 1000 stamina <<<< [(1000-200)/112.5] 7 seconds to kill with destro and still have left over magica from the mana bar
Edit.
Corrected the one handed dmg value on deadric sword non-upgraded.
Corrected the time bonus for faster dual attacks.
Corrected the avaible power attacks based on test from this post: http://www.gamesas.com/index.php?/topic/1279078-2419-armor-6399-damage-using-smithing-alchemy-enchanting-only-33-perks-329k-backstabs-post-3/page__view__findpost__p__19432824