A frog statuette would greatly help, since you can run much faster as a frog (enemies may still be hostile, but will have much less chance of attacking you). Pause the game when you stop running to look for doors or levers, etc. IIRC there is at least one door you need to open to get to the exit.
level 1 map spoiler screenshot
There are health and mana shrines you can use repeatedly. Do you have a bow or ranged magic attacks? Hit and run tactics might help when you can not just run past an area. Areana went through Iona's dungeon at about the same level as you, or maybe a bit less, trying for the lowest possible character level finish.
If you washed the dishes in the castle, the cook would have given you a strange spice bottle, which is actually a shadow potion.
There is an easier method to duplicate items which can be stacked;
Drag a stack out of (or into) your inventory (or container) and hold down the control key before dropping. This will bring up the split stack pane; type in a negative number and hit enter (the checkmark will be greyed out). This can also be done in the trade window.
