I'd allow it in games I Dm.
The first line of explanation is always the most useful "it's 'Magic', it doesn't Have to follow the laws of physics."
Also as has been said there are plenty of ways to work it out in a fluff sense to work too.
In the campaign I am playing in I have a pc with a bow that has shocking, flaming, and frost. However the Dm of that campaign does Not allow them to stack, I have to "pick one" if I want to use one of them. Pretty disappointing...It would be so much lethal if they did stack.
Another pc has a greatsword with keen, speed, and a +3 bonus.
They all work together at the same time- why not the elements too then?
It makes sense that a freakin sword can have Sentience but not that something could both freeze and burn? Say what?!
Heck they could go off consecutively instead of the "exact same time", sort of a "double tap." blam blam-
Sorry if that sounds rantish- (although it is so I'm sure it probably does!! ha-ha) and then he wonders why I never use the thing
-go figure...
