question re weapons rating

[Brann]

Hi
Bear with me for this possibly inane question.
How do you read the weapons rating for an item? For example, if I have a sword that's 1D10 +1 and one that is 2D4+2, which is the better one?
I get the bit about Thac0 and various other bonuses/penalties, but things like 2D4 confuse me.

Can anyone explain?

[Curdis]

The answer is, of course, statistical!

With the whether you hit or not

A 2d4+2 weapon (all other things being equal*) will hit 5% more than a 1d10+1 weapon. This is due entirely to the + factors being +2 and +1 respectively as to hits are rolled on a d20 die (d=die, die=singular of dice=plural). Each addition of +1 moves the probability 5% towards certain success.

With the Damage

A 2d4+2 weapon will do 1 to 4 + 1 to 4 + 2 points of damage per hit.

The average damage on a d4 is 2.5 = ((1+2+3+4)/4)

So the average damage per hit of a 2d4+2 weapon is 7. The minimum is of course 4, and the maximum 10. It is somewhat useful to express this as 4~7~10.

A 1d10 weapon will do 1 to 10 =1 points of damage per hit.

The average damage on a d10 is 5.5 = ((1+2+3+4+5+6+7+8+9+10)/10)

So the average damage per hit of a 1d10+1 weapon is 6.5. The minimun is of course 2, and the maximum 11. It is somewhat useful to express this as 2~6.5~11.

Putting it all together.

Let's assume a THACO of 10. In 20 hits:

The 2d4+2 weapon will hit 12 times (10 {THACO}+ 2) dealing an average of 7 damage. 12x7=84 points or an average of 4.2 points per attempted hit.

The 1d10+1 weapon will hit 11 times (10 {THACO}+ 1) dealing an average of 6.5 damage. 11x6.5=71.5 points or an average of 3.6 points per attempted hit.

Clearly the 2d4+2 weapon is superior.

*All things (i.e.) weapon bonus verses AC type, Speed factors etc. are never equal. - Curdis !