Did you talk to Malcom in the merchant's guild in Verdistis and agree to kill Maria to join the guild? If so, Maria will not talk to you.
The smith in the dwarven halls in the dark forest would also be a good one to check for axes, though he may not have anything better than the Ars Magicana smith.
There is a merchant in the area at the end of the game that may sell axes, as well as a couple potentially good axes consistently in the same places (don't recall if they are one or two handed).
Even with Assassin's Kiss maxed, I think you can do more damage with a sword than dagger. Save the game before completing the holy item quest, and you will be able to check out the stats on the holy dagger and sword. You may also want to consider the holy amulet, potentially the best amulet in the game, since there are other powerful swords consistently in the game (including one that can be found in the final area, which is potentially the best sword in the game).
If you are playing a fighter type character and mostly buy spell books rather than invest in mage spells, then you should have lots of spare skill points, and can afford multiple weapon expertise.
Free skills, and spell books you can buy (spoilers)