Adder Strike, does it use only one dose or two?

[Firebug]

Adder Strike, does it use only one dose or two?
This feat allows you to poison 2 "weapons" (unarmed strikes) in a single action. Does it take one dose of poison for the use of the feat (1 dose->2 poisoned weapons), or one dose of poison per weapon (2 doses->2 poisoned weapons)?

Adder Strike:

You can quickly apply poison to gloved hands, protected feet, or other protected body parts, delivering the poison with your unarmed strikes.

Prerequisites: Poison use class feature, Craft (alchemy) 1 rank, Improved Unarmed Strike.

Benefit: As a swift action, you can apply one dose of contact or injury poison to two body parts that you use for unarmed strikes. You must still protect yourself against exposure to contact poisons you apply in this way.

Normal: Applying poison to a weapon or single piece of ammunition is a standard action.

[Fuzzy-Wuzzy]

The grammar is clear: one dose, two weapons.