On the Xbox, holding the left trigger down will zoom the camera in to an almost over-the-shoulder view, and your character will remain fixed on a specific opponent. I'm not sure if this is available in the PC version. As a dragon I sometimes found this handy to automatically follow dragon generals, etc, that you had to hit repeatedly to take out (ie if you left them too long when they dodged they could be fully healed by the time you got back to them) or with opponents near the edge of your range (that you might not be able to attack fast enough if they were only in range for half a second). I never bothered using this as a human; as a dragon you just need to be careful that you don't automatically to follow an opponent into an anti-dragon shield, or too close to wizard towers, etc.
A few people have had problems doing damage to some opponents, a couple of which were with the goblin general on the path at the start of the fjords, by the teleporter. Often leaving the area and returning would correct the problem, or in one case someone simply jumped off the mountain in the fjords, and when they worked their way back up the path later they were able to do damage as normal.
If you still can not target Svadilfari, try emailing support@larian.com, with a description of the problem and possibly a link to this topic.