Certain pieces of armor and weapons can be "socketed" up to five times and then augments can be added using the arms lore skill. You can get socket scrolls from treasure chests and BODS and I'm sure other places. If you look at most players carrying a shield you will see that it is socketed with 4x +5 parry and has shield of spikes. Those are the 5 augments that were socketed to this shield. This is pretty end game stuff though because it is SO expensive. Sockets run around 50 ED each or 5 mil and depending on the augment it can be just as expensive if not worse. You might get a deal here and there but as a general rule of thumb adding +25 parry to an item(which is pretty common) costs around 50 mil or 500 ED. I am pretty sure that the wiki will have good information on this topic because it has not changed a whole lot, but I hope you find this low level explanation at least a little helpful.
First of all, thank you for helping Zoltan
but I would like to change a few things in your post which I think different.
Augments; they can be socketed into items using the item identification skill, not armslore. 100.0 skill level is enough to do it with 100% success (maybe even less skill level is enough, I am not sure)
Socket scrolls; you can find them by treasure maps, SOS and fellucca dungeon treasure chests (a custom system running in our shard, you can check wiki or NEW guild hall for more info about them, I did write books for sharing my experience with both puzzle and dungeon chests
) and I believe it is not possible to get from BODs anymore (I am not sure either)
All non-rare augments and socket scrolls are 50ed each on the stones at socket display (public moongate>>displays>>socket display). The common market price is 45 ed or 4.5mil for each socket scroll though, as I experienced in the last few months.
One more thing about socketing skill augments; each item can have a total of 5 lines + skill bonus. So, basically, if the item has naturally 2 different skill bonuses (for example a ring with +10 animal taming and +10 animal lore) you can only socket 3 more skill augments (like 3 x +5 animal lore).
I haven't tried it yet though (since it is a waste) but I think it is POSSIBLE to socket more, it just won't have/show the skill bonuses after the 5th.
You can send me a PM from here or ingame, I will do my best as soon as I see your message
I am sorry if any part of my post was not clear, cause of my English. Either, if you realize something wrong, please feel free to fix me.