Cerebro-Energetic Extension

Cerebro-Energetic Extension, Psi Weapon or Psi Sword is a Tier Four offensive Psionic Power and a weapon in System Shock 2. This Power temporarily replaces Psi Amp with a melee Weapon of Psionic energy. Its duration depends on the player's PSI and equals PSI × 10 seconds. Overloading this Power does not affect it in any way!

General Melee Strategies

 * Strength increases the final bonus added to the melee damage and thus should be a high priority.
 * Both Lethal Weapon and Smasher O/S Upgrades (acquired preferably in that order) substantially increase the damage output of a melee weapon, and should come in handy throughout the whole game.
 * Contrary to popular belief, OSA Agent is arguably the best class to specialize in any melee weapon, as one can unlock the following Psionic Powers at the (very) beginning:
 * Psycho-Reflective Screen that protects against 15% of almost all damage (Year 1, Mission 3)
 * Psychogenic Agility which can be used to catch up with enemies on early maps (Year 3, Mission 1)
 * Adrenaline Overproduction which can greatly increase melee damage (depending on one's PSI), allowing the player to literally smash any foe in one hit
 * Recursive Psionic Amplification that boosts PSI statistic, influencing all Psi Powers
 * Psychogenic Strength that increases the final bonus to the melee damage
 * Localized Pyrokinesis which makes the player immune to the explosion of Protocol Droids (and also Laser and Blast Turrets), eliminating the greatest threat of any melee weapon user
 * Neural Decontamination that efficiently protects against radiation, useful on Deck 1
 * Observe the attack patterns of enemies and always try to evade when they are about to strike. Agility can make the job easier for obvious reasons. This is especially important in case of Pipe Hybrids and Cyborg Midwives.
 * Shotgun Hybrids are one of the tougher opponents on early stages, as they have hitscan weapons. It is hard to defeat them without taking any damage being already in their range. However, the player can hide, attack them from behind and circle-strafe, buying enough time to finish them before they turn and start shooting.
 * Protocol Droids are very hard (close to impossible, actually) to defeat with melee weapons safely, therefore keeping a ranged weapon in one's inventory is advised.
 * The other approach is to run away to avoid the explosion at just the right moment when they go into self-destruct. Going around corners is very useful. Lots of practice and high Agility are recommended.
 * Enemies with no melee attack at all, including all types of big Robots, always prioritize getting some distance before attacking. That means as long as one stays very close to the enemy, it will keep walking back instead of attacking the player, giving enough time to defeat the foe. This strategy stops working efficiently when an enemy does not have enough space to flee.
 * This strategy also applies to all types of Assassins, but they can fall back at a very high speed, easily putting the player in a tough situation.
 * All big Robots have their only weapon mounted on their right side, the other one being harmless. Approach them preferably from their left side using the above strategy to avoid their attacks.
 * If they follow you, make sure to go clockwise. They can shoot at you even if only a part of their weapon protrudes around the corner, so going anticlockwise is discouraged.
 * Turrets are best attacked at close quarters - that is, if they can be reached. Cutting the distance and circle-strafing around them doesn't give them a chance to fire at you. Moving fast in front of their line of sight makes them unable to lock the aim and shoot.
 * With enough skill the player can jump over the Turret to stand on top of it, thus being safe from its attacks.
 * Rickenbacker Turrets cannot hit if the player standing too close to them.
 * Rumblers are essentially fast walking tanks and are to be treated as such - with extreme caution. Learning their movement helps, but not entirely, as they can surprise the player with an almost instant attack.
 * Grubs, both types of Monkeys and Infant (to some extent also both types of the bigger) Arachnids are most effectively attacked when crouching. It is best to retreat when attacking Grubs and Arachnids. On the contrary, it is recommended to charge while dealing with the Monkeys.
 * Attacking the Eggs can be tricky because of their contents. Depending on their type, a different strategy has to be chosen:
 * Black Eggs can be called sitting ducks, as they trigger no effects... yet.
 * Grub Eggs are the least harmless. After the Grub hatches, the player should fall back to attack it.
 * Swarm Eggs have a simple strategy: trigger and run. Afterwards they don't cause any problems.
 * Toxic Eggs are the toughest to deal with. While the flying spores can be easily dodged when crouching, the gas cloud will affect the player most of the time. Sometimes it can be avoided by approaching from above or from around a corner, but generally it is not possible to evade it. Melee-only players have to either stack Anti-Toxin Hypos, use Psi Toxin Shield, or be prepared for frequent visits at Resurrection Stations.
 * Standing below Security Cameras (if possible) eliminates their threat entirely.
 * Moving (ideally circle-strafing) directly below Psi Reavers makes them unable to aim and shoot at the player.
 * Swarms cannot be harmed using any melee weapon.

Psi Sword Specific

 * This Power can be unlocked as soon as on Engineering Deck (at its beginning on Easy difficulty ; at its very end on Impossible). If you're playing a pure melee character, you might as well focus only on this Power. While the Crystal Shard is better, it needs roughly 2.4× Cybernetic Modules to be Researched and maximized - yet still it deals similar damage to half-Mechs and cannot deal any to SHODAN. Laser Rapier, on the other hand, only excels when fighting pure Mechanical foes.
 * The biggest drawback of the Psi Sword is the limited time of availability. You have to recast the Power each 1:20 at best, thus it's good for short, intensive fights, but not for regular exploring. Keep a Wrench or some other weapon handy for those.
 * The Weapon's damage cannot be upgraded, no matter the PSI level. All other bonuses apply, however.
 * While its range seems the biggest, it's actually the shortest, though Wrench's is only a tiny bit longer.
 * Psi Powers cannot be cast while the Psi Sword is active (even if they can be pre-selected). Changing weapon or unequipping the Psi Amp cancels the Power.
 * It also stops working in case of saving-and-loading, leaving the current map using e.g. a Bulkhead or dying.