The Dagger, the Wound, the Jaw and the Axe of Sion

So I caught some tweets by Grumpmonkey, who worked on Sion as he was in development, and he was asking us to have a bit of speculation about stuff, namely the following:

"The dagger in Sion's head. We thought of it like the key in the ignition. The last bit of the ritual. Who's dagger is it?" "Also the metal jaw could be interpreted as some sort of ancient crown... " "Also Sion's axe...doesn't it look like a less refined or early version of a certain hand of Noxus's axe?"

From further tweets I got some further info:

• The gaping hole in Sion's stomach is where Jarvan I lspeared him pretty damn hard
• That metal jaw is probably the old crown of Jarvan I, worn and twisted

So I wanna ask for opinions and theories! What are your thoughts on the similarity of axes between Sion and Darius, on his jaw probably being the crown of Demacia's king and on who's dagger is stuck in Sion's head, and what it has to do with everything?