The description says that “Your Energised Attacks have increased cleave”.
However, this description could use some more detail. I can’t read code so I can’t pinpoint what it exactly does, but I know a few things:
It seems to enforce a target limit of 3. With a Sunder powered swing, I can hit 3 ragers, 3 crushers, 3 reapers, 3 plague ogryns, etc.
The cleave value itself seems to be untouched. With a group of 40 poxwalkers which have all been knocked to 7 hp with a grenade, a sunder swing only kills 12 of them, which is to be expected with a 75% Cleave Targets powersword (11.5 cleave). Though, if I do smack into a few poxwalkers and then into some crushers, I can still hit two crushers.
The game is currently filled with that type of description, that leaves out important information (or in some cases is simply wong).
I started this list a while ago, attempting to point out all of the issues with descriptions.
Maybe they will fix it some day.