When picking up a Sigil in Multiplayer, it should pick up a complete Sigil. It may be an idea to have separate Sigil types based on the number of pieces you have for possible mapping purposes. Picking up the Sigil item in Vavoom multiplayer only gives you the first Sigil piece.
The first Sigil piece has a little mark that shows the focus of the lightning attack. This mark actually moves. In Vavoom, this mark is stationary.
The fourth Sigil piece is a missile like attack like the Doom Renevants do. It has the ability to home in on its target. In Vavoom, it is more like a plain missile.