• All the Slayers fall into 7 groups. Abyss, Arachnid, Elemental, Fey, Humanoid, Reptilian and Undead.
• Each group has a Super Slayer that will increase damage/success on all monsters within that group.
• Each of those groups have an opposing group. (i.e. Humanoid vs. Undead)
• Slayer Weapons will do double damage to the monsters they are meant for.
• Slayer Weapons can both be found as monster loot and be crafted by using a runic crafting tool.
• Slayer Spellbooks will cause most spells to do double damage to the monsters they are meant for.
• Slayer Spellbooks can only be crafted by scribes using a scribe pen.
• Slayer Instruments will increase your success chance by 20% when used on the creatures it is meant for.
• Slayer Instruments will decrease your success chance by 20% when used on the creatures from its opposing group.
• Slayer Instruments can only be found as monster loot.
• A successful use of a Slayer Weapon, Spellbook or Instrument will yield a little white flash on the monster.

The Slayer Weapons were an unexpected addition, or rather an extension, to the world of Ultima Online. The following facts were known about them before Age of Shadows:

• The Slayer Weapons were only found on greater creatures and confirmation from an OSI representative placed their rarity slightly higher than that of silver weapons.
• A Slayer Weapon did double damage to the monster it was meant for. A successful hit with the weapon yielded a little white flash on the monster.
• All the Slayer Weapons fell into 6 groups. Each group had an opposing group. Weapons of a particular type were only found on their opposing group. For instance Balrons and Daemons would give Slayer Weapons that did extra damage to Elementals.
• When used against their opposing group, it would result in the monster doing double damage to the person wielding the weapon. For example, carry silver, and Repond creatures did double damage to you. Carry Repond weapons and undead creatures did double damage to you. Pick your opponent with care!
• Each group had a Super Slayer that would do increased damage to all monsters within that group.
• The Slayer Instruments were released with Publish 16 in 2002, long after the weapons were released, they worked the same way as the weapons except instead of doing damage to the creatures they were meant for, they increased the chance of success when using bard skills on them.
• The Slayer Spellbooks were released with Publish 31 in 2005 as part of an attempt to make mages more balanced in PvM.

• When looted from a Juka Lord, they first have to be modified by a GM Bowyer before they can be equipped.
• A GM Bowyer modifies these bows by double clicking the bow and then targeting a gear (made by tinkers).
• A modified bow changes its color to a dark grayish tone.
• The bows may only be equipped with chars of at least 80 DEX and 80 STR. This refers to the unmodified stat, so you can still wear an armor that will drop the DEX below 80.