The Sword of the Gods (near the end of the game) and the Nobleman's Sword (mid to late game) are potentially the best one handed swords (at #1 and 2, respectively), but there are other good swords, as well. IIRC purchased bastard swords are one handed, and can have quite good stats (check with the smith in Ars Magicana). Seth drops a potentially good sword (one handed, I think) if you kill him before the healers leave Aleroth (if you cast Poison Cloud near an NPC, but not directly on them, they will take damage but not turn hostile, and you will not loose any reputation). The Singing Blade, dropped by Pedro in the Ars Magicana sewers, can also be good...
Here is an old topic about One Handed Sword
s, with relevant discussion and links to a couple other topics. Screenshot links are all broken by now, but the majority of stats got typed as well.
If you save before running your mouse cursor over a chest or NPC (or hitting Alt nearby) you can open/trade and reload if you don't get something useful. Usually it isn't worth the time, though, unless maybe you are looking for spell books or charms, etc. You could also just check back more frequently; merchant inventories reset after about 10 to 15 minutes real time (depending on the NPC), though they can hold on to some stuff you sell/trade to them (which stays at the top of their inventory list).