Which Power Weapon?

Following up from the analysis of Chaos Terminators in the New Chaos Space Marine Codex, this post deals with the thorny question of which power weapon we should select if given the choice.  Throughout the new chaos space marine codex, it does not specify any kind of power weapon to be used.  We are therefore free to model all four different types of power weapon on our miniatures.  But which one?

Let's start by looking at the stats for the power weapon varieties.

Power Swords: these have AP3 and use the user's strength.  

Power Axes: AP2, S+1, but go at Initiative=1 due to being unwieldy.

Power Mauls: AP4, S+2, and concussive.

Power Lances: AP3 and S+1 on the charge, moving to AP4 and user's strength thereafter.

But in which situation(s) should we select each?  Without knowing what kind of army we may be facing, its hard to optimize.  But, let's think about each in turn and play to its strengths.

Power Swords.  These are the basic variety with an important AP3.  These are the swords that are going to be getting rid of enemy space marines (or equivalent).  I'd suggest that they are very appropriate on squad champions for the new chaos marine codex where each champion has to challenge every turn.  If we knew with certainty that the enemy was not going to be space marines, then I'd hesitate, and probably choose a power maul instead -- they still go at initiative, but have a superior strength which will aid with taking down pesky eldar (etc.) with higher certainty.  On chaos terminators, these might need some modelling or conversion work

Power Axes. These are the only option to get back to AP2, as per 5th edition rules.  And what would we use AP2 on?  Clearly terminators, but also those occasional 2+ save regular power armour worn by some space marine commanders and their ilk (e.g. Chapter Champions, Honour Guard), as well as Blood Angels' Sanguinary Guard, Ork Mega Nobs, Tau Broadsides, Tyranid Tyrannofexes (etc.).  The main drawback is that they go at low initiative, so we need to address why we don't take power fists (or chainfists) instead. They're not so much more expensive to obtain on a chaos terminator upgrade.  But to save on points, a couple of axes inside a Chaos Terminator squad might not be a bad idea so that they can go toe-to-toe with other terminators and negate their 2+ armour save, get a better roll to wound and force invulnerable saves.  We're really taking power fists in preference to power axes as a deterrent to dreadnoughts, monstrous creatures (and similar) to tackle their high toughness or AVs. If we're talking about a character in a squad (rather than terminator squads as a whole), I'd want them to be going at initiative unless they're plague marines or other infantry that go at I less than 4 -- in which case I'd still prefer power fists instead of power axes (again, unless I'm saving on points to afford other things elsewhere and suspected they could weather going at low initiative -- just like plague champions).

Power Mauls. Higher strength, worse armour penetration such that space marines still get their armour save.  Is this better or worse than a power sword?  Here's some quick math-hammer.  Suppose we set up the target of the power maul and sword as a regular space marine, and the wielder as a nasty chaos terminator.  The probability to hit is the same in both cases (4+).  The probability to wound is 2+ for the power maul, and 4+ for the power sword.  The marine gets his regular save against the maul, but no save against the sword.  So the combined probability to cause a wound on a marine is 0.138 per attack for the power maul, and 0.250 per attack from the power sword -- approximately twice as good!  Then again, if we're facing a terminator instead, then clearly the power maul is going to be better: 0.042 vs 0.069 unsaved wounds per attack -- i.e. power mauls aren't too much better against terminators, so we might as well opt for the powerfists and chainfists instead.  So, my take on this situation is that a power sword would be better on a squad character (especially if we know we're facing other marines), but a power maul would be better if we knew we were facing (e.g.) Eldar.  In a squad of chaos terminators, a few of these are not a bad idea as a deterrent if we're facing off against lower save armies.

Power Lances. These are interesting.  I would take them in preference to power swords if I could almost guarantee that I would get the charge in and potentially finish the job in under two game turns.  This means taking them on fast moving miniatures -- such as bike-riding characters for the main part.  The other main use would be to take them on miniatures riding in assault-ramp-equipped vehicles -- land raiders and the like.  So in a squad of terminators that might be heading for combat with marines, an odd power lance might be good!  But I think I'll be only taking them on Chaos Lords on Bikes for now.