Blunt Retort

When this defends a weapon attack, you may remove a +1

counter from the weapon.

Blade Break

Rulings

From the Mastery Pack Warrior release notes

Blunt Retort’s first ability will only trigger when defending a weapon attack. This is an optional effect: you choose whether or not to remove a +1 counter from the weapon it is defending when it resolves.
If a +1 counter is put on a weapon from a sharpen effect, then it is removed from Blunt Retort, the weapon is still considered to have been sharpened.

Keyword notes

Bladebreak - Equipment that are fragile and break after being used to defend. If you defend with a card with Blade Break, destroy it when the combat chain closes.

When you defend with a card it remains on the combat chain until the chain closes, therefore you cannot defend with an equipment multiple times on the same combat chain.
When this card is destroyed, it is sent to your graveyard.
The ability becomes a layer on the chain when the combat chain closes.
The Blade Break ability becomes a layer on the chain when the combat chain closes.
The ability goes on the stack when the combat chain closes.

All keywords

ClassWarrior

TypeEquipment

SubtypesHead

Defense1

KeywordsBlade Break

SetsMPW