Well that finally settles all doubt on the Plastic Shadowsword, this picture appears to be from a german issue of White Dwarf, I came across it on Warseer, however first credit appears to go to "Anung Un Rama" on DakkaDakka.
Excitingly according to a translation of the text below the picture by Darnok on Warseer,
"March will see plenty of new Apocalypse releases""
"the best thing about it: this is only one out of six superheavy variants, that you can build with parts from the box!"
We can only speculate on what those might be, but that must surely include at the very least Shadowsword (Volcano Cannon), Stormsword (Hellhammer Cannon - by IA:Apocolypse) and Stormblade (Plasma Blastgun). There is also the possibility of the Stormlord variant of Super Heavy Assault Transport (Transport Capacity and Vulcan Mega Bolter) as appeared in Apocolyse:Reload, this has been heavily rumoured with a number of CAD images also spotted, it seems likely that this would also be one of the options fromt this kit.