So Shadowmourne lore wise was an idea whipped up by the Ebon Blade to create a weapon that could potentially match Frostmourne. It used Arthas' hammer as a base, a ton of saronite, would become more powerful with each soul is stole, and is even forged with fragments from the Frozen Throne itself. While it may have never been as powerful as Frostmourne, it shared many of its features. It truly was a powerful weapon, and gameplay reflected that.
However, after ICC ended and Cata started, there is no mention of Shadowmourne. The DK class campaign doesn't mention it at all, and in fact frost DK's forge two mini frostmournes themselves during Legion. But those swords had a lot of it's energy absorbed away from Sargeras' sword, and with SL coming up, you would think Shadowmourne could potentially be a useful weapon against the Jailer and Sylvanas. Yet neither Darion nor Bolvar acknowledge it's existence, brining up the question if Shadowmorne even existed at all in lore.
So is Shadowmorne a canon weapon still you think? Or was it the case of blizz wanting to create a long process of making a very powerful weapon in Wotlk's conclusion? Do you think Shadowmorne could show up in some way in SL in the future?