Lockpicking is useless, not because it's not required for some chests (it never should be), but precisely because the keys are never far away. Lockpicking could be useful for traps though?
Pickpocketing is completely useless, and even if you want to try it for the fun, you can test it with pickpocketing gear and the pickpocketing trait (pump up to 3). It's a time loss on citizens, and you can't do it on merchands when you need it the most. Once you can do it (if you ever can, I didn't even test actually, I just noticed I coudn't seal Cyseal merchands, it said I didn't have enough experience, so I have to outlevel them?) you can buy whatever you lack anyway.
Bartering is mostly useless because, again, you can go up to 3 with trait/gear, and it doesn't have the impact advertised anyway as said here.
Luck Charm is useless because you can more than max it out with crafting and the trait. 2 daggers and 1 chest piece at crafting 5, 2 rabbit rings and one rabbit belt at crafting 2, and find/buy boots with lucky charm on it. 2 + 1 + 2 + 1 + the trait = 7 lucky charm. Starting level 8, you can find shields with 2 lucky charm on them, for a total of 8. I don't even know if lucky charm is good to have past 5.
Anyway, in retrospective lucky charm even maxed out never gave me anything oustanding with the exception of a few ruby cristals (so rare because it competes with all the junk loot anyway). It's mostly a goldmaking ability that would require a lot of swapping (a little bit time sink, but typically you do some swap on the exploration character with perception gear aswell so why not throw in lucky charm) and absolutely 0 point in it.
Loremaster is kinda useful, but you only need 2 out of combat (you can examine mobs from far away), rings and necklace helps you reach 5. And this bonus is so common that you probably can have it even on your fighting gear on your loremaster character so you never have to swap gear in and out of combat.
Furtivity is useless except one point for rangers so they can pick the guerilla talent and snipe (one time only per fight usually, preferably as opening, in case of oneshot the mobs don't even notice). This can be abused if you explore Hunter Edge before doing any combat. And Crossbows crits are very helpful in that regard.
Crafting/Blacksmithing is the king. It's a money making ability (just craft stuff with low cost composants like logs), it can significantly improve gear and significantly improve a character (a specific elemental resist can be pumped up on 5 pieces of equipment, 6 with shield, typically from 50% total (lvl 5-6? if you want to spend that much gold at that level) to 100% (without counting the shield). It can give 1 2 (or 3 on item lvl 22) secondary bonus STR or DEX if a man at arms or a scoundrel/ranger want to use hybrid abilities (which usually need between 8 9 or 10, or 3 4 or 5 bonuses in total) with tormented souls (double that on dualwielders). It can add elemental damage (and tenebrium) on weapons, on top of improving their base damage. And even at low level it allows you to bootstrap STR/DEX/INT, charisma, lucky charm and loremaster (keep/buy bones/skulls, teeth, rabbit paws, tusks and stardust herb, worse is having to buy pixie dust as is).
About the fact that merchants restock every hour (I thought it was at level up? Could it be both?),
it is indeed to deter savescumming. But it seems a little buggy and frankly, exploitable (I have a hunch you can influence it by keeping specific actions like dialogs and RPS minigame available in case you don't like your loot/merchant, and reload + activate one of them to perform a "reset" and get different items/loot).
As for the merchants loot quality difference between both version, my memory is a bit fuzzy because there were only three tiers then (blue green orange) and there's 5 now. But I admit that some bosses drops can be disappointing (especially since, due to the high disparity between bonuses' nature, a legendary weapon can be less interesting than a blue one same level).
Some bosses drop unique loot, which is a good feeling usually. One unique loot that I thought was sick is the sword of holy flame (lvl 13), but I read it's a random loot.
BTW I think that spellbooks are fixed (not random ever). And the only unique book I found was turtle stance (do not respec if you have it and like to use this ability).
