Andor's Trail

Every collector seems to be only interested in extraordinary and legendary items. However, I was asking myself if there was any other rare item, or even common item which are dropped by pure luck and THAT WE CAN'T BUY IN ANY STORE ?

Do you guys know if there is a list of those items (if they exists...) ?

By "luck"? No not really. The game engine works off of mathematical drop rates. Almost every monster drops common and/or rare items. I'm pretty sure that there is not one dropable item that can't be bought in a shop.
There is a very old list on the forum that shows what items monsters drop, but it is not up to date.

Arulir skins?

Good one. I didn't really put much thought into it.
Claws too.

Viper amulet
Any "animal" part
Most gems and crystals, although a couple can be bought in stores.

Yeah, mostly animal parts can't be bought in stores, but I was asking myself more about weapons, shields, etc...

Some drop weapons. Others drop boots or gloves.

BWM sword and dagger,
Black axe, axe of fear
There are a few others. But all weapons, armor that are dropped other than LE/Ex
can be bought

There are a few others. But all weapons, armor that are dropped other than LE/Ex
can be bought

Uh... I don't think so. For example, no armorer sells stone clubs... or even polished necklace and Iqhan pendant. those items are ONLY dropped by monsters.
And knowing that andor's trail item list (http://andorstrail.irkalla.cz/0.7.0/itemlist.php) is not updated, I assume that there might be some other items I never get which are dropped by any kind of monster... and that I wouldn't be able to get without any list...

That website was an old fan site, not maintained by the dev team. If some current fan wanted to pick up the pieces and update it, no one would cry.

Just saying.

Except maybe for you, the first time you didn't get it updated within 20 seconds of a new release, and the forum blows up about why that new cool helmet isn't listed yet...