Well, the ST table works like this:

Code:

ST sw thr nsw nthr
10 1d 1d-2 1d6 1d2
11 1d+1 1d-1 1d8 1d4
12 1d+2 1d-1 1d10 1d4
13 2d-1 1d 1d6+1d4 1d6
14 2d 1d 2d6 1d6
15 2d+1 1d+1 1d6+1d8 1d8
16 2d+2 1d+1 1d6+1d10 1d8
17 3d-1 1d+2 2d6+1d4 1d10
18 3d 1d+2 3d6 1d10
19 3d+1 2d-1 2d6+1d8 1d6+1d4
20 3d+2 2d-1 2d6+1d10 1d6+1d4
and so on

Basically, use this conversion:

1d-3->1d2-1

1d-2->1d2

1d-1->1d4

1d->1d6

1d+1->1d8

1d+2->1d10

1d+3->1d12

If the bonus exceeds +3, and there is more than one dice, use this table:

2d+4->1d12+1d8

2d+5->1d12+1d10

2d+6->2d12

This has the funny side effect of turning per die increases into increased dice sizes:

+1/dice->Increase all dice by one step

Beware, this will make damage more random, while it keeps the average damage the same. This will mean that when before, the armor protected almost all the time, and sometimes left a small amount of damage in, now the armor will negate more attacks, but when it gets penetrated, the chances that the damage is significant exist.

EDIT: basically, this is an alternate convert to dice. Instead of referring to the tables above, the rule is simple: Get Dice+adds as usual, and then for each +3, convert 1d->1d12. Then, if you can, "spend" a +2 to convert 1d->1d10. Then, if you can, spend a +1 to convert 1d->1d8. If you have negatives, every -1 converts 1d->1d4, and if you have leftovers, every -1 converts 1d4->1d2. Any leftover -1 are applied to the total.