Prediction: The spear is the Spear of Destiny
So a DLC named Revelations, which has flashbacks to the Slayer's past, mention of his name Taggart, possible glimpses of his family and Daisy. It makes you wonder what else they will bring up.
According to John Romero, Doomguy is a descendant of BJ and Commander Keen. Now I do wonder if that's what is happening here, why the name Taggart? Maybe Keen gave him another name for protection or something.
But anyway the spear has 3 prongs and a gem in the middle. Obviously the design is a bit different, but you can see the similarities. And here's the thing, it's been in Hell before, and so has BJ.
>Upon capturing the Spear, however, B.J. is immediately sucked into Hell, where the Angel of Death awaits to challenge him to find out if he is worthy of wielding the Spear of Destiny.
https://wolfenstein.fandom.com/wiki/Wolfenstein_3D:_Spear_of_Destiny
Will they go all-in with the revelations and tie it to Wolfenstein? Maybe even Keen? Maybe even Quake 3 Arena?