Hello, and welcome back to Lotro! This is indeed in the wrong thread but worry not, I shall try and answer your question anyways: unfortunately it is not possible for a player to create a "cosmetic copy" of items they own and give that copy to anyone else. I think what the person you spoke to was referring to was either the wardrobe function (which creates cosmetic copies for use by any character on your account), or the "Ceremonial" cosmetic version of a few armour sets that are available in the store. As the wiki page you listed states, the Burglar set from Dunland has a Store version called "
Armour of the Thief-lord", however I am not sure if this is still available for purchase or not.
This armour set isn't exactly the kind used in the Burglar character creation though - the chestpiece is the same (this chestpiece only comes from Dunland quest rewards, which are BoA, and
Dial-crus, which is Bind on Equip and drops from the Pits of Isengard. So you could ask a friendly high-level if they wouldn't mind farming this instance a couple times in order to get it for you), but the hood is from the
Burglar's Enedwaith set. You can barter this set for Marks and Medallions at Harndirion in Enedwaith - the Wiki says you need to have completed "In Their Absence, Chapter 15" in order to barter, and so won't be able to sneak there as a low-level, but I'm not totally sure that this is the case anymore - I would ask if someone could check this for you (unfortunately I can't atm).
Most likely though, I would say you are best off trying to find some of these armour pieces in Lalia's Market or the Store, if you can't wait til higher level to get them - up to you! You can try and have a search for someone to farm Pits of Isengard for you but tbh you probably won't have much success - most people who go looking for this item just wait til they've levelled to 65 or so and just grab one of the many quest rewards that share the appearance.
Hope this helps, and apologies it's not quite as easy as you were hoping
