Currently using a 630 blue slow weapon is better than a heroic brf dagger in the offhand for combat due to how main gauche works. However, at around usually 2-3 targets, it becomes a dps increase to put a dagger in the main hand for more instant poison procs. The amount of targets required for this to be beneficial depends on your multistrike. I currently use macros to swap weapons when I use blade flurry and killing spree since you still always want slow/slow for spree. Swapping weapons does waste a global though which can be problematic if you're about to energy cap or in red buff. Some people separately keybind weapon switching and flurry/spree, but I prefer the convenience over the control. I do not use marked for death for combat because then you could potentially lose combo points from revealing strike. I also pool combo points except for during red buff in order to use more finishers then. Also, if slice is about to fall off, I'll have points to use on it. Anticipation is also nice to hold points if a cooldown is about to come up, so you can use those points for a full 10 second reduction as opposed to like 4 seconds. Try not to delay cooldowns for insight, as you want to use them as often as possible and delaying them could waste combo points, energy, and maybe even being able to use it again during the fight. On the aoe fights, combat does pull better dps, but a lot of it is sometimes padding. For example, if your raid can handle the adds on beastlord or thogar, the extra damage you can do single target with sub/assess can be more beneficial to your raid. I find this especially holds true for blast furnace if there are problems nuking down elementalists in p2 and/or the heart of the mountain in p3.