I can add to this a bit

First the mighty YNK released the Epic Weapons. These were highly desired because their stats were far beyond anything available in the exchange market. Also they were pre-forged, ready to use, were pre-reinforced to +7 and based on the highest tier weapons of the time. The more rabid Rohan players jumped all over them even though they had an obscene price of 26,000 RPS ($260 US) in the item Mall. They were sold only 2 times. Once on a weekend for about 4 hours, and a week later for a couple hours only and never again after that. Needless to say that the very limited sales period had made a small number very happy players and a large number of very, very angry players. Many of those player left in what I like to call The Great Rohan Exitus where a several hundred of its players walked away from Rohan and are to this day playing on private servers or other less frustrating games.

A year or two later, the bean counters at YNK had another epic brainfart and sold high-end weapon parts called "Upgrade" 1.0 parts. These were based on the same tier of weapons as the Epics. They had a rash of sales over a few months where they would sell one of the parts per month for the princely sum of 4000-6000 RPS ($40-60US) per part - which worked out to be about $200 US just for the the parts. These were different from Epics different in that you had to forge and enhance them yourself into what is known as Upgrade 1.0 weapons. Because you forged them yourself there was some minor variation of the amount of DD, leech, mobility and/or other capabilities. You also had to reinforce (+) them yourself. By the time you finished buying the parts and the supplies you needed to forge them you were usually spending about $300 US or more each. Because there were more Upgrade weapons as opposed to Epics, those players that could not afford the expense of them slowly left the game to find some measure happiness elsewhere or move to the non-epic server.

The populations of the servers slowed down more and more over the years, despite the efforts of YNK Gods to periodically open "No Epics" servers like Divinity to appease those that did not want to compete against holder of those epic and upgrade weapons. Things rolled along like that for a few years with a server merge or two until the population dwindled to the point where it was simply not feasible to maintain an epic-free server. So to appease the masses left playing on the non-epic/upgrade Jin server, YNK decided to offer upgrades to the players of both servers for a time. These "Upgrade 2.0' weapons were much better than the previous "Upgrade 1.0" or "Epic" weapons. Also they were based on the next tier glacial weapons. The parts were sold for 2000 rps each and there were a few months of sales for these. By the time you forged them you would spend about $100-$120 USD if you had decent luck. Many did and for a while there were many, many upgrade 2.0 weapons. Those moving to Jainus from Jin were much happier being able to come with Upgrade 2.0 weapons in hand.

A couple months after the merge the Upgrade 2 sales ended. After several complaints of players returning to Rohan after a long hiatus hoping to finally get in on the action and not being able to make these weapons. To appease the arrivals Almighty YNK made the mistake of blessing them with them not Upgrade 2.0 parts, but Upgrade 3.0 parts at the same prices as the older upgrade 2.0 parts. In many cases the end weapons made from Upgrade 3.0 parts were slightly superior to the Upgrade 2.0 parts by offering marginally higher DD and attack percentages. This raised the questions and ire from all of those that bought and forged Upgrade 2.0 weapons as to why another level of them was necessary so soon after the last upgrade sales. Why not simply sell the Upgrade 2.0 parts again for a little while? Lord YNK remained deaf to the prayers of its player base, but did close the sales of Upgrade 3.0 weapons after only a relatively short period.

To this day PlaywithI/YNKi has remained deaf to the prayers of its remaining small playerbase so the only place you will be able to acquire such a weapon is from exiting players that bothered to put theirs up on the EM before they left.