There doesn't seem to be a whole lot of consistency with the different domains, but we have so far:
Primordus - Fire and Conflagration
Jormag - Ice and Persuasion
Zhaitan - Death and Shadow
Kralk - Crystal and Fury
Mordremoth - Plant and Mind
DSD - presumably Water and something else.
Conflagration seems as though it could mean fire or conflict/war. It would be a little odd to have Fire twice.
Without seeing a pattern it's hard to speculate as to why the domains would have been devised this way. Am I missing a correlation here?
Conflagration, Persuasion, Shadow, Fury, Mind. Seems odd that Jormag would have domain over persuasion which seems oddly specific compared to the rest.
I wonder what the intention of this design was in terms of the natural cycle of life on Tyria.
Also thinking in terms of opposites and weaknesses, why Primordus and Jormag? Is it solely fire versus ice? Is it conflict versus persuasion?
Was just trying to think of what the DSD could be but some of these just seem a little too random and like there isn't much of a point in trying to find a pattern.