1: Kajhit have a Racial Ability that gives 15 HTH damage.
2: The perk in heavy amour that increases HTH using gauntlets.
3: The Gloves of Pugligism that a reviewer found in Riften on a theif. I think it's +15 again.
Now, Kajhit + gloves = 30 HTH I beleive. I don't know for certain if that works, but in a certain footage the highest sword power I think was 17. Granted it was steel, but it was still 13 lower.
4. Now, I think (Once again, not certain) that being a Werewolf boosts you HTH again. I don't know how much or if it applies in human form, but with the above, that's 30 plus a boost.
Finally, considering we don't really know if HTH is it's own stats or if it comes under One or two handed, there is the possiblity (Not garenteed) that the perks from one of then can affect it.
Now, I may be WAY wrong here, but if not, HTH MAY be a viable option yet. Someone either ask Pete or ask someone who already has the game to test it.

Even if not it can get to 50.