Wych Weapons : The Stats
The Dark Eldar codex allows for wyches to be equipped with a variety of exotic weaponry at the bargain of 10pts per weapon although they are available in limited numbers to Wyches and slightly more can be fielded in a similar sized unit of elite Bloodbrides.
The Shardnet and Impaler is essentially a net and trident but can take several forms (such as the hooks in Lelith Hesperax's Hydra Gauntlets (formerly Hydra Knives) are punching gloves covered in a variety of blades and spikes. Old hydraknives were double bladed hand weapons.
Razorflails (formerly Razorsnare) are essentially blades on chains allowing for better reach and accuracy as well as the ability to easily hit critical points on an opponent.
The weapons' confer the following bonuses:
Shardnet and Impaler - counts as 2 ccws; Enemy models in BTB contact loose 1 attack
Hydragauntlets (formerly Hydra Knives) - counts as 2 ccws but gain +d6 attacks, rather than the normal +1
Razorflails (formerly Razorsnare) - counts as 2 ccw; re-roll failed to hit and to wound rolls
While the Shardnet and Impaler fulfil an entirely different, defensive role, both the gauntlets and flails seek to assist damage output. However to assess the viability and determine which is optimal for your army selection some numbers need to be crunched.
The results are shown below, there are no results for WS9-10 as these are not encountered that often. Additionally 'WS3' results obviously apply to WS1-3 due to the way to hit rolls are calculated.
For ease the MEQ statline (WS4, T4) is highlighted below although only 1/3 of these again will actually kill a Space Marine due to his 3+ save.
As you can see unless you roll 5-6 attacks the flails are slightly better although the weaker the opponent the less of a factor the razorflails become and more attacks are important. However the painbringer combat drug makes the re-rolling to wound effect of the razorflails redundant.
Finally the raw data from my spreadsheet is below as I do not know how to create a proper wiki table.
Weapon Normal flail Gauntlets+1 2
Attacks 2 2 2 3 4 5 6 7
Hits vs WS3 1.333333333 1.777777778 1.333333333 2 2.666666667 3.333333333 4 4.666666667
Hits vs WS4+ 1 1.5 1 1.5 2 2.5 3 3.5
T3 @ WS3 0.666666667 1.333333333 0.666666667 1 1.333333333 1.666666667 2 2.333333333
T3 @ WS4+ 0.5 1.125 0.5 0.75 1 1.25 1.5 1.75
T4 @ WS3 0.444444444 0.987654321 0.444444444 0.666666667 0.888888889 1.111111111 1.333333333 1.555555556
T4 @ WS4+ 0.333333333 0.833333333 0.333333333 0.5 0.666666667 0.833333333 1 1.166666667
T5 @ WS3 0.222222222 0.543209877 0.222222222 0.333333333 0.444444444 0.555555556 0.666666667 0.777777778
T5 @ WS4+ 0.166666667 0.458333333 0.166666667 0.25 0.333333333 0.416666667 0.5 0.583333333