Spell/skill speed.

[Kotemon]

What I mean is: It may be impossible for them to add a 'Speed' stat due to the inability for a single stat to govern both spells and weaponskill in this capacity.

What he said ^

Right now Skill speed affects a weapon skills cast/recast timers and physical dot potency. Magic skill affects only Spell cast/recast timers and magical Dot/Healing (regen/bubble) potency. While merging the two makes sense for simplifying things. That could only work if both physical and magical timers and DOT's were exactly the same. After all changing one effect's timer or potency could do something unintended for other things if they were all lumped together.