The Iron skin is something existing all the times if u add? I don't c it on the right or left click button though I have it as combat skill.
Question about items:
I try to understand why some items, like rings mostly, that cost so much (fast cast rating) seem useless to me. I tried to choose which of 2 items to keep by comparing which is more expensive, but many times I c huge difference without reason.
Iron skin is a "passive" skill. Meaning any points in it are just always active nothing else you need to do.
Do NOT go by how much you can seel something to determine its usefulness. Game mechanics seem to play a lot of "worth" as in terms of gold on things liek pluss skills which might be totally useless to your char. Figure out both. What mods and items your specific char needs AND what tends to sell for most gold. Keep the ones in the former category for ur use and Bring the others to Charsi for Repairs/shopping/gambling/merc resing purposes.
There's a pretty obvious reason why items values can't be classified by selling price : a crappy barbarian item can be extremely good for a sorceress (like the FCR rings you mention) : so how would you classify it ? Extremely cheap or extremely expensive ?