Ok, after the treachery of the baron, I've gone all the long way down to the Wyvern Pass. Talked to the soldier who wants water and then gone down to the next spot, killed everything around there. I then can't ride the mule back to him with the water, that's a big issue for starters.
You should never be forced to take a skill to complete a major quest without warning, but that's besides the point right now. A friend of mine also plays and he rode the mule back to him, but it still didn't help. He even has a saddle on it if that's what's needed for it to bring the water to the soldier.
Either I'm not getting this or it's a bugged quest. If it's bugged, you can move this post to the dev thread or I'll repost it there. If it's not, any hints?
Tried searching the forum first but found nothing about this particular quest.