When using Weaponmaster's ability with Blade of Ruined King, do you still need to pay the non-power portion of the equip cost (killing a unit you control)?

Ruling: Yes, you must still pay the full equip cost of Blade of Ruined King, including killing a unit you control. Weaponmaster only reduces the power portion of the equip cost by 1.

Sequence:

• Activate Weaponmaster's ability targeting Blade of Ruined King
• Pay the equip cost: kill a unit you control, and pay the power cost reduced by 1
• Attach Blade of Ruined King to Weaponmaster

Nuances:

• Equip costs that only require power are shown in the [Equip X] tag format
• When an equip cost includes non-power requirements (like sacrificing a unit), the full cost is written out with a colon separator
• Weaponmaster's reduction only applies to the power portion of any equip cost