I played Skyrim in legendary difficulty for a long time but this time I noticed the difficulty rules placed by Bethesda is shall we say not to my taste. For me using combat AI mods here in nexus is the proper way of raising game "difficulty". The 1/4 is to 3 damage ratio for legendary difficulty is crap so I fired up CK and made it to 1 is to 3 which means your damage to enemies is not reduced but you still get the x3 damage from enemies. To make this simpler: Any weapons or damage-dealing spells will deal damage exactly as it says. So for example if you have a bow with 1000 damage (including all enchantments from rings, necklace, etc.) it will deal 1000 damage to enemies excluding the enemies armor rating.

To ensure a more balanced and enjoyable game I would recommend using mods that alters enemy AI instead.

Dragon AI overhaul mod:
Dragon Combat Overhaul by Apollodown (scripted mod)

Humanoid AI overhaul mods:
Combat Evolved by Crushboss (script-free)

Note: there are many combat AI mods search for it at nexus or google it. Me I prefer script-free mods as much as possible.

THANKS to:
Bethesda - for Skyrim
Nexus - for this awesome modding community
Bretton - for the heads-up in CK