Maximum damage in a single hit

Highest damage will be berserk double dagger sneak power attack with dagger boosting perks. The sneak attack will apply to both daggers and will have a 15x damage modifier.

However, all this is meaningless in vanilla. You can abuse the fortify restoration bug with smithing boost gear, and make weapons with thousands of damage, killing everything in one hit.

Expanded: If the goal is short fights, the best way is to focus on Smithing and hit 100 ASAP, then focus on Enchanting so you can make Fortify Smithing gear, then Alchemy to get the Fortify Blacksmith potions. Complete the excavation quest to get enchanting boosting gear in Dragonborn DLC, and also get the Black Book for the enchant and alchemy boost.

This lets you create weapons with damage way above your leveled enemies, and additionally armor that basically makes you unkillable. You don't even need perks at that point.