The effect does not actually steal life from the enemies Geralt strikes, as even if the opponent has almost no health bar left Geralt will still gain health accordingly to the damage he deals for the fatal blow. Meaning the more damage he deals the more health he gains, strong attacks will restore more health than fast attacks, a Riposte will restore even more, on the other hand if you use the wrong sword like silver against bandits and deal minimum damage the health gain will also become minute.

The health gain is directly linked to the damage Geralt deals when striking foes with the swords.

However, there is little to no sense in doing so, as apart from The Blasphemer's Outfit crafting the armor is usually the hard part, not to mention you will not gain the vampiric effect using other swords.

It is actually possible to use incomplete sets by replacing both Silver and Steel swords for other ones of your choice (except for those from a different cursed set of course).

It is coupled with 'demonic' hum sound effect.

When drawn, the swords in each outfit emit a screen effect which darkens your screen and removes some of the color.

For Kinslayer's Outfit the most difficult ingredient is Dragon scales.

For Oathbreaker's Outfit the most difficult ingredient is Draugir armor fragment.

For Blasphemer's Outfit the most difficult ingredient is Yellow meteorite ore (While not as problematic as the following 2 it may cause huge additional expenses if you are unable to find the required amount).

See the articles on each ingredient for tips on where to find them:

Each set has a difficult to acquire ingredient that may delay the ability to craft a full set.

Storing silver ores is also recommended since their refreshing rate in Chapter II is quite low compared to Chapter I.

Stock studded leather for chapter II Oathbreaker set if you are doing Iorveth path.

You'll need to spend a lot of Orens and crafting ingredients, so you might wish to prepare for that.

Tips for Crafting the Dark Mode Exclusive Outfits: However, given that they are cursed, the swords provide no benefit and harm Geralt by sapping him of Vitality as long as the outfits to which they belong remain incomplete. The swords included in the outfits strip opponents of Vitality while supplementing the witcher's. Once all their components have been collected and donned, the Blasphemer's, Oathbreaker's and Kinslayer's outfits provide great advantages in combat. In addition to raising the difficulty bar, the mode includes several new sets of equipment/items that are linked through a dark legend detailed in the Journal. Under this setting, each and every foe represents a significant challenge. The 'Dark' difficulty setting is the most demanding difficulty level in gameplay terms besides Insane, which features similar difficulty but with saves becoming unusable upon death.

Dark armor witcher 2