The holy sword is potentially one of the best one handed swords, though there is another that can be found late in the game. For the holy sword, the best available damage is 71-100; people have reported buying one handed baslard swords with higher damage.
Searching for 'best sword', etc should bring up several topics listing other possibilities.
If you quick save before running your mouse over an item/chest/merchant or hitting the alt key, you can identify the item or trade with the merchant, then quick load to get different stats or inventory. This can be done repeatedly to get the best stats or specific bonuses on an item (save after finding good candidates) or looking for specific items (such as spell books or charms) from merchants.
Augment Damage helps a bit, as does the damage bonus from strength. For secondary stat calculations, see;
differences between classes (minor spoilers)
or
Early Starter Tips (NON-Spoiler Version) (contains much of the information in the above topic).
