The reason why anyone would get extra recovery is to reduce potion usage, not because they are struggling with health management. And doing the ark at level 20 should be quite easy for anyone really, you can make do with 20 medium heals, 10 shock resist pots, and 10 mana pots, if you make use of...
If you're looking for a good spirit weapon, you can use paladin's longsword, not a light weapon, but a good substitute.
You can't go to ashen wastes before you need to complete the quest to talk to the pirate captain about ashen wastes.
Doesn't ancient fang have 4-10 damage? Spirit breaker has higher damage with 6-9+ 4(spirit).
You should still be fine without ancient fang, though I imagine the beast slayer attribute helps with sunken citadel. Rng is jerk sometimes, so good luck if you're going to farm for it.
I'll agree with most on what you said, but I can't use sacred fire in the ark and it's a huge drain on mana if you just spam it, and I don't really feel like using it every 3 seconds and stop attacking, but hey, that's just my playstyle.