Each type of enemy is more vulnerable to certain damage types, and generally they are most vulnerable to at least one elemental damage type.

You can convert a portion of your weapon damage to an elemental damage type using a gem in your weapon, up to 50% with a pristine gem, however the benefit is not as great as it may seem for melee weapons.

The 50 Strength perk gives a +10% damage increase to light and heavy basic physical attacks.

The 100 Strength/Dexterity perk gives a +5% damage increase to Slashing/Strike or Thrust respectively.

This means if you have at the correct attribute perks you can get a +15% damage to your light and heavy physical melee attacks.

If you convert a portion of your damage to elemental, that portion no longer benefits from these perks.

So, for example, if you use a Pristine Topaz to convert 50% of your hatchet to lightning, it will appear that it should provide a net +15% damage increase against Ancients. Against Ancients slash will deal no extra damage, but lightning will deal an extra 30%, so with half of your damage converted to Lightning, that would appear to provide a net +15% damage increase.

However due to the Strength attribute perks at 50 and 100 Strength your physical attacks gain +15%, which the elemental side of the damage does not benefit from.

Therefore, you only effectively get a +7.5% net damage increase. If you consider that gems like Diamond or Opal can give you a flat +15% increase (if you meet their requirements), using an elemental gem can actually lead to less overall DPS.

The advantage to the elemental conversion is that it is a flat predictable amount. Also note that the 50 strength perk only applies to basic attacks, so depending on your ability usage, it may still be more beneficial to convert if you primarily use abilities.

This does mean that there are several cases that converting to elemental damage will generally give an actual damage decrease, assuming you have the required attribute perks, so you should never use these:

  • Lightning War Hammer vs Ancients
  • Fire Great Axe/Hatchet/Great Sword vs Angry Earth
  • Arcane Spear/Rapier/Bow/Musket vs Corrupted