The Spiker is the Brute equivalent of the SMG or the Plasma Rifle. It has two barrels which gives it a decent rate of fire. I fires long spikes for ammunition. Like many Brute things it is also equipped with two vicious bayonets on the front which prove deadly in close combat. The Spiker may be dual wielded. It was introduced only in Halo 3
These are also almost exclusive to Brutes. These grenades will like the Plasma Grenades stick to almost anything including people but these blast radius isn't a ball. It's like a cone so you could in theory be standing next to one and not get hurt. But this is not always the case. Many times the spikes will bounce off of walls and such.
This is very similar to the fabled weapon that Tartarus wielded in the second game. The Gravity Hammer is a very effective close range weapon. It has a radius of about 6 feet or so then it's ineffective. Like the other melee only weapons this will allow you to lunge towards your opponents at short ranges.
Brute chieftains are armed with this weapon. It was introduced in Halo 3