Editing Warhammer 40,000/8th Edition Tactics/Space Marines (section)

===Melee Weapons===
*'''Chainsword/Combat Knife:''' Still the basic Close Combat Weapon profile, but it's free and allows for one extra attack, so it's good against enemy hordes. All your sergeants can take it alongside the main gun, so it might be worth it to swap that bolt pistol he's not using anyway. Combat Doctrines make these invaluable for turn 3 deep strikers with AP-1 (although for them, the Bolt Pistol also gets AP-1)!
*'''Paired Combat Blades:''' Found on Incursors and some Lieutenants.  No extra attacks, but unmodified hits of 6 score an extra automatic hit.
*'''Eviscerator:''' A two-handed Chainfist with variable damage on a model with at most 2 attacks. It competes with a power fist with Assault Marines.  It is a fucking awesome double-handed chainsword, though.
*'''Lightning Claws:''' SU AP-2, allows you re-roll to wound, and grants an extra attack if you have two of them.  This will outperform a Power Axe against anything with T less than twice your S, particularly now that it's barely more expensive.  Often your best bet for mulching single-wound hordes.
*'''Relic Blade:''' Available to Honour Guard, Vanguard Veteran Sergeants, and Captains. S+2 AP-3 D1d3, so it's like a Force Sword or Stave but better (and strictly better than a Force Axe both in absolute terms and because it costs ''less''). ''Better than a Power Fist'' against most infantry-sized targets. Costing as much as a Power Fist, consider whether the better accuracy is worth the +2 Strength gap between the Fist and the Blade. One of the advantages over the Power Fist is that effects happening on 6+ to hit can actually trigger with the Blade since it has no hit penalties.
*'''Power Weapons:''' Each type of Power Weapon has its own profile now, so pick the right one for the situation. All Power Weapons have a damage value of 1:
**'''Power Axe:''' S+1 AP-2. A good enough compromise between the Sword's armour negation and the Maul's brute force; typically your best choice, despite costing more than the other two, because you have to pick one to take before knowing what you're going to need killed, and this has the best overall performance in the T3-T8 Sv2+-Sv6+ range you care about. 
**'''Power Maul/Power Lance:''' S+2, AP-1. This is the one you want to use against lightly armoured units that rely on toughness to shrug off hits. The Lance is identical to the Maul because of reasons.
**'''Power Sword:''' S User AP-3. Best against targets that rely on armour saves over toughness to shrug off hits. Except against frail things with good invulns like Crusaders, who ignore AP anyway.
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*'''Mathhammer:''' Note that we do not take into account the chances to hit since they do not vary for the 3 weapons we are looking at. Results are expressed in percentages. We also assume that the weapon is wielded by a basic Space Marine, so with Strength 4.  
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{|class="wikitable" border="1"  cellpadding="4"  cellspacing="4"
! colspan="2" |Target
!Power Sword
!Power Axe
!Power Maul
!Winner
|-
| rowspan="2" |TEQs
|Terminator (T4; 2+/5++)
|33.33
|33.33
|22.22
|Power Axe and Sword
|-
|Terminator w/ Storm Shield (T4; 2+/3++)
|16.67
|22.22
|22.22
|Power Axe and Maul
|-
| rowspan="2" |MEQs
|Space Marine (T4; 3+)
|41.67
|44.44
|33.33
|Power Axe
|-
|Captain or Chaplain (T4; 3+/4++)
|25
|33.33
|33.33
|Power Axe and Maul
|-
| rowspan="4" |GEQs
|Hormagaunt (T3; 6+ or no save)
|66.67
|66.67
|83.33
|Power Maul
|-
|Guardsman, Guardian (T3; 5+)
|66.67
|66.67
|69.44
|Power Maul
|-
|Aspect Warrior (T3; 4+)
|66.67
|55.56
|55.56
|Power Sword
|-
|Sister of Battle (T3; 3+)
|55.56
|44.44
|41.67
|Power Sword
|-
| rowspan="4" |Other
|Tyranid Monster (T6; 3+)
|27.78
|22.22
|25
|Power Sword
|-
|Light Tank or Monster (T7; 3+)
|27.78
|22.22
|16.67
|Power Sword
|-
|Medium Tank or Monster (T8; 3+)
|13.89
|22.22
|16.67
|Power Axe
|-
|Heavy Tank or Monster (T8; 2+)
|11.11
|16.67
|11.11
|Power Axe
|-
|}</div></center>
As you can see, it is extremely hard to draw a clear winner between the Power Axe and the Power Sword. It is, however, easy to see that Power Mauls/Lances are crap, only superior when fighting units that will already die in droves to bolter shots or won't die easily to anything due to good invulns. What's easy to remember is that the Axe is stronger against Marines (that you'll face a lot), the Maul is best against Storm Shield Terminators or anyone else with a good invuln, and the Axe is best against most of the tanks. Power Swords have the edge on most things relying only on their armour saves, while Axes scale better against tough things. What you choose between the two is a matter of preference, meta, and gaming group.  The special case for Mauls is Toughness 5, where the Maul is best down to Sv3+ and the sword and maul break even on Sv2+, due to how powerful it is to move from 2/6 wound chance to 3/6, but T5 are relatively rare to begin with.
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*'''Force Weapons:''' Librarian power weapons with D1d3 instead of just 1, but they cost around the same as a Power Fist. They lack Sx2 but have no penalty to hit. Useful if you're going to hit characters or multiwound models like Primaris.  All of them are overcosted compared to a Relic Blade, with the Force Axe as the worst offender of the lot.
*'''Chainfist:''' Sx2 AP-4 D2. Marginally better than a Power Fist against Vehicles and other highly-armoured invuln-lacking models. Costs only 2 points more than a Power Fist, so paying extra for better AP and more reliable damage could be worth it.
**Never forget, you can swap to your basic CC weapon if you don't want to give up accuracy - against low toughness single-wound enemies without a penetrable save, like basic daemons, this can often be better.
*'''Power Fist:''' Sx2 AP-3 D1d3. -1 penalty to hit rolls, which can be annoying. Good against everything, quite cost-effective.
**Never forget, you can swap to your basic CC weapon if you don't want to give up accuracy - against low toughness single-wound enemies without a penetrable save, like basic daemons, this can often be better.
*'''Thunder Hammer:''' The weapon against which all others compare, and boy are you paying for it: NOW 40 POINTS FOR CHARACTERS (16 points for units). A Power Fist that always deals 3 damage. The extra reliability could mean the difference between one-shotting a Custodian Guard/Aggressor or getting a Guardian Spear/Power Fist in the face. When you have a Thunder Hammer/Storm Shield-Captain with Jump Pack every enemy model begins to look like a nail, but at over 4x the cost of a Power Fist, its not worth ditching up to three extra special or heavy weapons just to squeeze out a few extra points of damage. Still quite viable on everything that isn't a CHARACTER, at least.
**Never forget, you can swap to your basic CC weapon if you don't want to give up accuracy - against low toughness single-wound enemies without a penetrable save, like basic daemons, this can often be better.
*'''Dreadnought Combat weapon:''' Allows your dreads to beat up things, allowing them to swing at SX2 (S12) AP-3 and flat D3 with no accuracy reduction. Redemptor version hits at D1d6. Dread chainfists found on contemptors and ironclads are AP-4 and D4.
*'''Seismic hammer:''' Like a dread fist but with AP-4 and D5!!!! Imposes a -1 to hit... But one single smack with this is all you need to kill most HQs and cripple tanks. With shock assault ironclads hit 5 times with this weapon for a potential 25 damage!
**Absolutely garbage, because anything that can take this can take a chainfist instead, and the damage boost is either exactly offset by the accuracy penalty, or the accuracy penalty is worse, depending on circumstances.  Always take the dreadnought chainfist over this.