Against EB: Feather until your attack makes the Abyssal blade more powerful. After that use the blade for attacks and feather for spy actions. At war, always use your best NON-percentage based weapon. (Feather, Soulreaper, the blue candycane, whichever is best) You're more likely to get fails using the blade when you are low on troops.
Lvl 4 feather^ **** lvl 1 feather ********. At this point I'd recommend the red paladin ring of zealots lvl 10 over sword though. xD
So feather is better than abyss for hansels troops, but for spies, abyss would be better? I don't want to switch every time lol.
For on hand equip...soul reaper or abys based on cs. Chainsaw whip is next, followed by feather. Sickle let's you hit some eb.
Just stick with the feather until you get the whip, these items are better in eb for the last few hits so you don't have to use pots or mith. Also, it can give you a few extra hits from less extra troop loss, giving more gold in the long run.
IGCB: I don't bother switching for haunts, but I do for FoD and above. I have enough attack from other items that I never fail on haunt, but I'll fail the last hit every now and then on FoD if I don't use the blade. Once you get up to around 3 mil spy attack you'll start to notice a slight difference with the blade on spy actions. I suppose a bigger bfa and it wouldn't matter, but I'm not really ready for that yet.
*I fail the last hit every now and then on FoD if I don't use the feather. Confused myself on that one, lol.
My new bow and hands allow me not to have to item haunting. FoD I use 7.5 still. I don't really want anymore attack buildings. I enjoy my hansel. My laziness prevents me from switching weapons, especially when I skim.
At around 47 million static attack bonus and you won't have to use pots on FoD at all. If I'd had this equipment earlier, I probably wouldn't have bothered with the extra attack buildings.