Because I couldn't. Turned it down to hard, which is actually more enjoyable to play on anyway.

I didnt find it especially hard. The only hard part was when i was controlling Seltrik fighting agains the first three knight spectres. Why it was difficult? Because now parry takes a bit of your health and in this fight you have to parry a lot because Seltrik cannot roll over as a witcher to avoid hits.

Some advice I can offer is master the counterattack (riposte) feature. It's the only advantage you'll have in combat without having the ability to roll to dodge.

When fighting the elemental you'll have all your witcher skills at your disposal. Lay a Yrden trap and immediately roll out of the way as it charges you. Get behind it when it's stunned and slash him with strong attacks. You should get in at least four good hits before you need to move again.

Quen will protect you against arrows, so will structures that can be used as cover - the deflect arrows skill comes in handy, too. Fireballs - just run - you've got plenty of space to do so. It may seem you are trapped in a small area, though, contrary to what you might think, nearly the whole battlefield is open to you.

Good luck.

Dodge a lot, no frontal attack AT ALL. So moving around quick and make use of your magic helps a lot.
Some even later fights on dark difficulty had me abandon swordplay entirely (Igni is quite handy in those cases!)

4:47 here: http://www.twitch.tv/aphox/b/296264209 (although that guy got quite lucky)

In some circumstances its freakin impossible. I was playing as alchemist to make Dark even harder, and first part of Eternal Battle took me half of a day. No vigor from magician tree for parry, no male combat skills from swordsman tree for survival. And in first part of battle, the one with banner, in Dark mode solders that are running with You are slain in a single hit and You end up facing 4 knight spectres and one Draugir alone... I was just about to give up, eventually managed rather by luck than skill, but my angry yells probably were heard by all my neighbors.

Well not having the option to roll sucks and the riposte icon doesn't appear (for me at least), but it's not that hard, wraith fall from 4-5 sword swings and killing the Draug with the Oathbreaker set was easier than killing it on Normal.

It can be killed in 5 strong swings to the back. Catch it with Yrden and bam.