Gem weapon enchantment question.

I am wanting to enchant my long sword with the drain life ability. I am confused after reading what is copy and pasted below. It has weapon, one handed weapon, ward gem, necro gem. What do I use please?

"
Necromancy Gem - Necromancy Ward Gem (Death - Onyx)
Corpse Explosion Power (+3) +35.8% Corpse Explosion Damage -30 Maximum Durability Chest
Death Attunement (+3) +17.9 Death Attunement 0 Wands
Heavyweight Death Attunement (+3) +35.8 Death Attunement 0 Staves
Death Ray Power (+3) +26.9% Death Ray Damage -30 Maximum Durability One-handed Weapon
Heavyweight Death Ray Power (+3) +53.8% Death Ray Damage -55 Maximum Durability Two-handed Weapon
Drain Health (+3) On Hit (10%): Drain Health -40 Maximum Durability Weapons
Life Resistance (+3) +17.9% Life Resistance 0 Chest
Near Death Power (+3) +17.9 Near Death Damage Bonus -30 Maximum Durability Chest

 

a long sword is a one-handed weapon, so the available enchantment will be Death Ray Power, not Heavyweight Death Ray Power. the enchantment becomes available if the sword is socketed with EITHER a Necromancy Gem or a Necromancy Ward Gem, both of which can be made from Onyx.

 

On the Enchantment Page it states states specifically:
When you socket a specific Gem or Jewel on a piece of equipment, a set of specific enchantments have a chance to be placed on the item along with the enchantments listed above, per item. These enchantments will only be available if the piece of equipment has a specific Gem or Jewel socketed on the item, and is different depending on the equipment piece.
These gem socketed specific effects do NOT work on Ranged Weapons.

Was something on the Enchantment page not clear for you to understand?