I can't completely answer the question but for claws the ones that can have skills are designated h2h2 and the lower level ones (weapon type h2h) don't get them
I guess they felt that 2 +3 Tiger Strike Katars at level 1 would be over-powered :)
(Ruvunal explained this at some stage, can't now find the post)
I can offer the following based on play impressions, not technical info. Take with a large pinch of salt :)
The following items can get skills as auto-mods:
Amazon: Amazon-specific spears, javelins and bows
Assassin: higher end claws (weapon type hth2)
Barbs: barb hats
Druids: druid hats
Necros: wands, heads
Pallies: sceptres
Sorcs: Orbs, Staves
As for number of skills it seems to be equally distributed between 0-3
As for skill level it seems to be equally distributed between levels 1-3
As for which skills appear it is always within 2 rows on the skilltab (the screen you get by pressing T). In other words an item can have a level 12, 18 and 24 skill but can't have a level 6, 18 and 24. 6 and 24 are too far apart
At the start of the game only levels 1 and 6 appear in the vendor. At around 6th level (not too sure) you start to see level 12 skills
As you progress through early Normal the skills you see gradually get higher. Eventually you only see level 30, 24, 18 (and I'm not sure about level 12) skills appear. Or to put that another way if you want to see low level skills, certainly level 1 and level 6 skills you need to farm Act 1 Normal or shop Akara or Gheed with a low level character. You will never find a + Corpse Explosion wand in Hell Cows. The Dark Wood is quite a good place to hunt out that wand or your Oak Sage hat or whatever it is you're looking for. It still takes a lot of patience :)
You can shop in higher Acts, providing you keep the character level low but you might have a problem seeing items as they have a minimum level according to type. In other words, Drognan won't sell Bone Wands to a level 1 character
After a while you stop seeing white and grey items in the shops - everything is magic. This can be a bit of a nuisance if you're shopping for runeword material
It's very hard to find a 2 socket wand with a level 1 or 6 necro skill for instance as the first two types only get one socket and the third type is qlvl 18. You should be able to see Bone wands at Drognan and Ormus, I'm not sure yet whether you can shop a white bone wand there. (Something I've been planning to test for a while :) )
Edit: found the claws
Type h2h (which can not get skills as automods):
Katar, Wrist Blade, Hatchet hands, Cestus, Claws, Blade Talons, Scissors Katar, Quhab, Wrist spike, Fascia
Type h2h2 (which can get skills as automods):
Hand scythe, Greater claws, Greater talons, Scissors Quhab, Suwayyah, Wrist sword, War fist, Battle cestus, Feral claws, Runic talons, Scissors suwayyah
I guess they felt that 2 +3 Tiger Strike Katars at level 1 would be over-powered :)
(Ruvunal explained this at some stage, can't now find the post)
I can offer the following based on play impressions, not technical info. Take with a large pinch of salt :)
The following items can get skills as auto-mods:
Amazon: Amazon-specific spears, javelins and bows
Assassin: higher end claws (weapon type hth2)
Barbs: barb hats
Druids: druid hats
Necros: wands, heads
Pallies: sceptres
Sorcs: Orbs, Staves
As for number of skills it seems to be equally distributed between 0-3
As for skill level it seems to be equally distributed between levels 1-3
As for which skills appear it is always within 2 rows on the skilltab (the screen you get by pressing T). In other words an item can have a level 12, 18 and 24 skill but can't have a level 6, 18 and 24. 6 and 24 are too far apart
At the start of the game only levels 1 and 6 appear in the vendor. At around 6th level (not too sure) you start to see level 12 skills
As you progress through early Normal the skills you see gradually get higher. Eventually you only see level 30, 24, 18 (and I'm not sure about level 12) skills appear. Or to put that another way if you want to see low level skills, certainly level 1 and level 6 skills you need to farm Act 1 Normal or shop Akara or Gheed with a low level character. You will never find a + Corpse Explosion wand in Hell Cows. The Dark Wood is quite a good place to hunt out that wand or your Oak Sage hat or whatever it is you're looking for. It still takes a lot of patience :)
You can shop in higher Acts, providing you keep the character level low but you might have a problem seeing items as they have a minimum level according to type. In other words, Drognan won't sell Bone Wands to a level 1 character
After a while you stop seeing white and grey items in the shops - everything is magic. This can be a bit of a nuisance if you're shopping for runeword material
It's very hard to find a 2 socket wand with a level 1 or 6 necro skill for instance as the first two types only get one socket and the third type is qlvl 18. You should be able to see Bone wands at Drognan and Ormus, I'm not sure yet whether you can shop a white bone wand there. (Something I've been planning to test for a while :) )
Edit: found the claws
Type h2h (which can not get skills as automods):
Katar, Wrist Blade, Hatchet hands, Cestus, Claws, Blade Talons, Scissors Katar, Quhab, Wrist spike, Fascia
Type h2h2 (which can get skills as automods):
Hand scythe, Greater claws, Greater talons, Scissors Quhab, Suwayyah, Wrist sword, War fist, Battle cestus, Feral claws, Runic talons, Scissors suwayyah