Wych weapons 2: Razorflail and Hydragauntlets

If defensive weapons are your thing, then you've already decided on taking shardnets (or playing Nurgle). If you're tossed up between the two offensive choices of wych weapon, come with me as I do some analysis.

Firstly, what do they do?

The razorflail, inspired by Ivy's blade from the Soul Calibur series, is a combination of sword and whip. In game terms it provides a re-roll to both hit and wound - pretty tasty, and a benefit that sharply increases with the number of attacks made.

The hydraguantlets are spiky cestus-like guantlets (duh) that bear a passing resemblance to Voldo, of the same Soul Calibur series as Ivy. Perhaps when the Grey Knights are redone they will feature a Hadoken attack? Anyway, hydragauntlets provide a bonus +d6 attacks, rather than a bonus +1attack for a pair of weapons.

Naturally, if the weapons could be combined on one model, they would epitomise awesome. Naturally, they can not be combined. So which is better?

I have looked at the expected return for each weapon, against a variety of infantry, and the results are below. By expected return, I mean the fraction that is the product of the probability of killing an enemy, and the number of attacks made. For the hydragauntlets, I have assumed an average of +3.5 bonus attacks in all cases, as that is the mean result of many d6 rolls - hence it is the expected value of the d6, in so much as it contributes to the models overall number of attacks.

I have also looked at the effect of combat drugs. There are four possibilities that directly affect the chances of scoring a kill, and two that do not (these two are collectively termed no drug). Finally, I have considered the effects of charging (let's be frank, wyches should always be doing the charging), and also the furious charge, should you score a couple of pain tokens.

Forgive my shonky coding, I'm new to this whole web thing.

Firstly, against Guard or equivalent (most effective option in bold)

vs GEQ	Wych	Razorflail	Hydraknife
No charge
No drug	0.444	0.889	1.000
+1WS	0.444	0.889	1.000
+1 S	0.593	1.053	1.333
reroll W	0.667	0.889	1.500
+1A	0.667	1.333	1.222

Charge
No drug	0.667	1.333	1.222
+1WS	0.667	1.333	1.222
+1 S	0.889	1.580	1.630
reroll W	1.000	1.333	1.833
+1A	0.889	1.778	1.444

Furious Charge
No drug	0.889	1.580	1.630
+1WS	0.889	1.580	1.630
+1 S	1.111	1.728	2.037
reroll W	1.185	1.580	2.173
+1A	1.185	2.107	1.926

In most cases, the hydragauntlets are superior to the razorflail. Because it is not too challenging to either hit or wound a GEQ, the rerolls conferred by the razorflail are of generally poorer utility than the extra attacks provided by the hydra. Incidentally, it can be seen that rerolls to wound and +1A are clearly the drug of choice for GEQ slaying; if a squad of 8 normal wyches and 2 hydras charged, rerolling wounds, the expected death toll is 11.66. Look out, blob squad; look out wyches! If you blow through too easily, that Hellhound will cook you!

Anyway, onto something somewhat more challenging - Orks.

vs Ork	Wych	Razorflail	Hydraknife
No charge
No drug	0.278	0.694	0.625
+1WS	0.370	0.823	0.833
+1 S	0.417	0.938	0.938
reroll W	0.463	0.694	1.042
+1A	0.417	1.042	0.764

Charge
No drug	0.417	1.042	0.764
+1WS	0.556	1.235	1.019
+1 S	0.625	1.406	1.146
reroll W	0.694	1.042	1.273
+1A	0.556	1.389	0.903

Furious C
No drug	0.625	1.406	1.146
+1WS	0.833	1.667	1.528
+1 S	0.833	1.667	1.528
reroll W	0.938	1.406	1.719
+1A	0.833	1.875	1.354

Against the T4, the razorflail's reroll to wound comes into its own. Naturally, it gains nothing when drugs provide the same alternative - in these cases the hydras tend to trump the rerolls to hit, as you would expect. For Marines and equivalent, we merely adjust these figures for the better save, which doesn't alter the relative utility. However, if you want to plan for expected casualties vs MEQs, here goes:

vs MEQ	Wych	Razorflail	Hydraknife
No charge
No drug	0.111	0.278	0.250
+1WS	0.148	0.329	0.333
+1 S	0.167	0.375	0.375
reroll W	0.185	0.278	0.417
+1A	0.167	0.417	0.306

Charge
No drug	0.167	0.417	0.306
+1WS	0.222	0.494	0.407
+1 S	0.250	0.563	0.458
reroll W	0.278	0.417	0.509
+1A	0.222	0.556	0.361

Furious Charge
No drug	0.250	0.563	0.458
+1WS	0.333	0.667	0.611
+1 S	0.333	0.667	0.611
reroll W	0.375	0.563	0.688
+1A	0.333	0.750	0.542

As an aside, it is worth noting that in most instances, the expected return of a razorflail or hydra is around double that of a normal wych; as the cost is double, the weapon option is worth taking in instances where the return is more than double. I find this to be the case often enough.

In summary, razorflails are generally better than hydragauntlets against T4+, and hydragauntlets generally do more damage against T3-. Keeping in mind that more damage against very shooty armies like Guard may actually work to your detriment, if the wyches wipe their enemies in one turn only to get nuked, then I must recommend the razorflail > hydragauntlet.

Especially if you want your own little Ivy :)