The English tooltip for Full Swing currently reads:
Additional Effect: Increases target's damage taken by 10% Duration: 15s
Whereas, other localisations specify "physical" damage, a pretty important distinction. For example, the German tooltip reads:
Zusatzeffekt: Ziel erleidet 10 % mehr physischen Schaden
To give credit, this was pointed out on the pvp subforum by the user: SuperZay.