It is possible that this could be a larger variant of the SH-B1 Plasma Saw that Vandal used in Dead Space (mobile).In the final version of the game, there are no usable melee weaponry accessible to the player(s), though it could have been finalized into the default Hydraulic Engine attachment which serves a similar purpose. In the announcement trailer for Dead Space 3, Isaac is briefly shown wielding what appears to be the plasma saw.Shen was killed by Hanson, a crazed security sergeant using a Plasma Saw.

The team then replaced their issued firearms with the Plasma Saws due to their greater efficiency. He came to their rescue, effortlessly slicing the Slashers apart with his saw. team made their first stand against a horde of Slashers. After all the blood and guts and carnage in the game, the needle in the eyes. You want a BLUE LIGHT for the laser before you jab it into Isaacs squishy eye. The needle activates the parts of his brain that the marker codes are stored and it planned to kill him to absorb his body with his brain all 'marked' up. Head into the machine and use the stick and ACTION button to aim and lower the needle.

Samuel Irons found a crate of these saws and viewed the find as a 'divine discovery', just down the hall from where the P.C.S.I. The marker tricked Isaac into using the machine.

Dead space 2 eye needle