Just a quick note, the best way to look at it is average damage. Average damage is calculated by adding the high and low of the damage die and dividing by 2.

So, a d6 is (1+6)/2=3.5, a d12 is 6.5. (It might seems like it would be 3, but 0 is excluded from the range, so the average is 3.5, not 3.)

Thus, 2d6 is 7 average damage per round, versus 1d12 at 6.5, therefore 2d6 will, on average, deal more damage than 1d12. so, straight up, a great sword is better than a great axe. Likewise a 2d4 redcap sickle (5 ADPR, is better than most other light weapons, like a rapier at 4.5ADPR.)

A magic weapons with a static +1 increase the damage die by one size (d4 to d6, d6 to d8, d8 to d10.)

Magic weapons with a static bonus also improve your to hit chances, +5% for each +1, so you need to balance how much additional damage you do and your improved chance to hit when comparing magic versus non-magic weapons.