Generally the average damages of weapons on Dawn of the Ages range from 12 to 18. Some special types, like the arena weapons, can and do exceed these averages, but they are very rare (special permission required, but 99.9% of the time they will be denied.) Below is a convenient table of damage averages followed by dice types that will give the weapon that specific average damage.
To read the dice types, there is a number followed by "d" followed by another number. The first number is the number of dice, and the second is type of dice. (We call these 'dice types' out of habit - there is no 1-sided die in the real world.) So, to make a weapon with an average damage of 14.0, consult the column "Average Damage", look for the average damage of 14.0, and choose whatever dice type that will give you that value. A dice type of 7d3 means "7 3-sided dice", which translates to a minimum damage of 7, a maximum damage of 21, and an average damage of (7+21)/2 = 14.
Average Damage Dice Types
12.0 1d23
2d11
3d7
4d5
6d3
8d2
12d1
12.5 1d24
5d4
13.0 1d25
2d12
13d1
13.5 1d26
3d8
9d2
14.0 1d27
2d13
4d6
7d3
14d1
14.5 1d28
15.0 1d29
2d14
3d9
5d5
6d4
10d2
15d1
15.5 1d30
16.0 1d31
2d15
4d7
8d3
16d1
16.5 1d32
3d10
11d2
17.0 1d33
2d16
17d1
17.5 1d34
5d6
7d4
18.0 1d35
2d17
3d11
4d8
6d5
9d3
12d2
18d1
18.5 1d36
19.0 1d37
2d18
19d1
19.5 1d38
3d12
13d2
20.0 1d39
2d19
4d9
5d7
8d4
10d3
20d1
20.5 1d40
21.0 1d41
2d20
3d13
6d6
7d5
14d2
21d1