Guild Wars 2

Description reads: (…) Using a shield skill will increase boon duration.

I’m not quite sure what it means. The only shield skill with a boon is Shield 4. Does it mean that it will only affect shield 4 skill?

Or does the description mean, increase all boons duration by 2 seconds when equipping a shield?

Or does it mean, after using a shield skill, your all your existing boons duration are increased by 2 second.

Using either the 4 or 5 skill on your shield will add an additional 2 seconds to the timer of existing boon for you and nearby allies.

cool, I thought that would make the most sense. Thanks.