This is a rule that I came up with to deal with the normally protracted combat with high-level characters vs large monsters, and to make the otherwise ubiquitous +1 sword feel like it actually has some real power. This rule basically adds an extra damage die per "+1" of a magic weapon. So a +1 sword would do 2-16 (2d8, 9 avg) points of damage, instead of 2-9 (1d8+1). This would also give a +1 sword: +3 vs Dragons more weight, as that already boosted +1 sword can do 4-32 (4d8, 18 avg) to a dragon in one hit! That would really hurt them!
This could be applied to high Strength, but that would make a strong character insanely powerful. As noted above, a character with a Strength of 18 could do a lot of damage in one hit! On the other hand, one could use the AD&D approach to eighteen plus Strength, by adding a bonus damage die instead of the normal static damage bonus for each point above eighteen. So a character who through magic growth or enhanced super-strength, as become as powerful as a Frost Giant (STR 21) can hit with a +6 bonus to-hit and throw four dice of damage in one hit, on top the ability to chuck big boulders like a Frisbee. Such a thing should be codified.