IRL : To be both inteligent, but most importantly wise (totally different things) to a near godlike level.
On The Internet : Specifically on the internet, to Leon_the_Great means to have such a total deep understanding of everything and everyone, that one can simply rise above anything, and look down at everything. The 'everyone' and 'everything' is absolute to the ultimate extreme, a total *.* of inclusion.
In essence, Leon_the_Great is the ace of trumps.
IRL : "So yeah this bomb went off in the tube train i was on this morning, but in a carriage further up thank god! Everyone was screaming and panicing and.. oh, it was just so terrible. This guy sitting next to me though.. just totally Leon_the_Greated out. Can you believe he kept on working on his laptop like nothing happened!! I mean come on, a bloody support beam had landed a few inches from his head, yet he gave it the briefest of glances and got back to work!"
On the Internet : "The other day i came into this internet textual verbal chat room, and as usual these steriotypical internet users were having a purely textual verbal battle. Seemed pretty higher class users too, no "ur mum", instead a whole torrent of massive perfect-grammared paragraphs with big words, well thought out intelectual insults at each other, pomposity and arogance seething from every word. Then this other guy who had been watching a while suddenly came out of the blue and COMPELTELY Leon_the_Greated them both in 3 lines. They had to retreat right back to some of the most blatent and deluded delusions i have ever seen, to prevent themselves from simply having to commit suicide.