Surprisingly perhaps, but various forms of melee weapons continue to be employed even in the distant dark future. Hi-tech melee weapons can be extremely potent, able to cut down power-armoured warriors with ease or ripping open armoured fighting vehicles. It must be remembered, however, that to use a melee weapon you have to get in close – the sword is still no match for the gun. Instead melee weapons see use where no guns are available or cannot be use, when ammunition runs out, or when ranges are very short. Adeptus Astartes storming an enemy fortified position will have the speed, protection, and missile firepower needed to get into melee range – and once they do it is game over for their enemies.

Primitive melee weapons: Primitive melee weapons range from a utility knife, via an underhive shiv, to the blades and other weapons employed on primitive worlds. Most primitive melee weapons lack the penetrating qualities required to overcome modern rigid body armour, but work well enough against unarmoured targets or targets wearing only primitive armour.

Vibro weapons: Vibro weapons are hi-tech versions of primitive bladed weapons that use power-material-oscillation technology (related to the technology use in power weapons) to create a weapons with a cutting edge that vibrates several thousand times per second. The minute (and completely invisible) oscillation effect helps the weapon cut through armour, bone, and flesh. The blade also gets very hot, despite integrated heat-dissipating feedback loops. Vibro weapons require power cells to operate. Without power they are useless; the cutting edge of a vibroblade is not very sharp. Vibro weapons are popular with scum and mercenaries.

Mono weapons: So called monomolecular weapons have a very narrow cutting edge, culminating in a single nano-strand of incredible hardness and durability, bound into a crystal-matrix mesh of high density and durability. Contrary to common lore it is not the cutting edge that is lethal – it is the matter-disruption properties of the backing material matrix that allows the mono-strand to cut through non-bonded materials with little effort. The Imperial Guard is issued with mono-blades, either as long fighting knives or bayonets.

Hyperdense weapons: Hyperdense cutting edges are similar to monomolecular weapons, except that their design involves sacred techno-arcana pertaining to the use of collapsed/hyperdense materials. The result is a cutting surface that is even more lethal than a monoblade – the collapsed matter will sheer through almost anything that isn't protected by molecular hardening or nuclear dampener fields. Given the difficult manufacturing process hyperdense weapons are found only in the hands of the rich or lucky. The Adeptus Astartes are neither, but as humanity's finest they have access to such weapons if they desire them.

Chain weapons: Chain weapons resemble bulky versions of normal cutting weapons. They contain heavy power cell in the hilt/haft which powers the cutting chain that gives the weapon its name (it strongly resembles a chainsaw – a common industrial tool). Chain weapons are almost always mono-weapons, since a chain weapon without this feature would have trouble dealing with heavy modern armour. Because of their weight and bulk chainswords and chainaxes are frequently employed by power-armoured soldiers. The Astartes are fond of chain weapons – the oversized chainsword with hyperdense cutting edge is a staple of Marine assault troopers, capable of cutting down other Astartes or peeling open lightly armoured vehicles. Another famous chain weapon is the Astartes Terminator chainfist – which is most correctly classified as a power weapon.

Power weapons: Power weapons are usually normal melee weapons that have a annihilation energy field installed. Running from a power pack in the hilt/haft, the annihilation field is the pinnacle of the matter-disruption effect used in mono/hyperdense weapons. Instead of a passive-integrated effect the active-effect field extends beyond the weapon and is the primary destructive agent; the weapon itself is of secondary importance. The power field interfaces with other power fields, so a power weapon can effectively be used to parry other power weapons. Some power weapons have a variable power setting – on low power they can play havoc an the target's nervous system, but won't kill (the Adeptus Arbites power maul is a typical example).

The Imperium retains some examples of pure-annihilation weapons. Such weapons forego the use of a material component, keeping only the hilt that contains power cell and field projector. There are several problems with such a system; the projection technology is lost-tech and the replacement system used to build such weapons is energy-inefficient, leading to a very short lifetime for the power cells. The main issue, however, is that the annihilation field has no mass or inertia, so that parrying becomes effectively impossible.

Force weapons: Force weapons have something in common with both hyperdense and power weapons; they are, in essence, hyperdense psi-foci that can channel a psyker's latent psi-aura into a destructive field akin to that produced by a power weapon. Since force weapons are fuelled by psychic energy they are of less use to non-psykers (but hey, a hyperdense sword is still lethal enough, it will hack a person in twain even if wielded by a mundane). Powerful psykers can channel power into the weapon, enhancing its lethality to the level of a power weapon – and beyond. Force weapons are very rare and quite expensive.