Well... first thing I'd do is lighten the level 1 load.
Kill Fighting Style entirely, bounce Spellcasting and Expertise to 2, and have Quarry, Knacks, and Guide at 1.
For Quarry itself I'd set it to 1d6 at level 1, Wisdom mod per long rest is fine. Though at level 6 I'd suggest letting them recover at the end of a short rest. Sort of like Bardic Inspiration. In fact, why not have it progress at the same levels as Bardic Inspiration as well to map out to the "Damage Breakpoints" where fighters get up to 4 attacks?
Duration on Quarry, though, is a bit tricky. I'd probably set it higher since you can't bounce it between targets. Say, 8 hours and allow the Ranger to select a Quarry off Footprints/Ectoplasm and Wanted Posters/Bounty Slips? Would definitely allow them to track their quarry long term that way, since you could burn multiple Quarry uses to track someone over long distances and through cities.
As far as the knacks I think they're pretty great, honestly. Love that you put favored foe in there rather than having it be a core class ability. Definitely allows players to opt into a historically iconic but also historically problem-riddled class ability! Great choice, there.
I will say having purely explorational options right next to combat options (Fell Handed, for example) is probably not a great idea. It's why A5e split out the "Secrets of Arcana" from the Eldritch Invocation list. I do like that you've got specific levels for them, so I might suggest setting up a secondary 'Grant' at specific levels for combat-oriented knacks like Fell Handed at 6th and 9th. Maybe drop the current 6th level requisite (advantage after landing a crit isn't -super- powerful) down to 4th, then do 4th, 9th, 13th, and 17th? It'd mean making a few more options and some tracks but it could be worthwhile.
Might also be good to sprinkle some Social options into the Knacks pool so players can choose to make a more socially skilled Robin Hood as opposed to only an exploration-focused Aragorn. (and even he gave a show-stopping speech at the Black Gates of Cirith Gorgor to Mordor)
Most of the rest of the class is perfectly fine. Though I'd absolutely make a note under Foe Slayer that any character that succeeds the save can't be forced to make the same save, again, the same day. Otherwise you could have you player throwing out 5 fingers of death on the same target and it should probably just be a punch.
nudge nudge wink wink Okay, that joke might be too dumb even for me.
