All knockback from any source, be it player spells, monster spells, item affix- applies 100% of the time to small units, 50% to medium, 25% to large, 0% to immune units like bosses, golems, spirits. And players are medium, so its always 50%
Some skills also have a chance to actually attempt to knockback, which means they have a multiplicative set of 2 rolls- telekinesis is 35%, molten boulder 50%, psychic hammer scales. That means telekinesis only has 17.5% chance to knockback a player.
Item based knockback ie clegs gloves, whether applied to ranged or melee attacks, has a 100% chance to attempt. That's still a 100/50/25/0 roll vs small/med/large/immune
When you dual wield weapons, only one weapon will be activate at a time and applying its attack modifiers, so knockback on gloves will affect both weapons but knockback on a weapon only affects that weapon, not the other.
Nice great answer, the last paragraph is what I was wondering, the rest I read on Amazon basin which is such a good resource.
Is the this the same with fools mod? I've read fools mod has odd ww behavior such as using the attack rating for the first hit opposed to each weapon having their own ar.