Yandere/Vouch

FYI, vouching someone isn't any skill or ability. You vouch when you are telling everyone that you are 100% sure that the person you vouch isn't yandere.

Strategies
You can vouch someone (perhaps civilian) whom you want to be killed by yandere. Yandere like to kill vouched people, and for a reason!

When you can not guarantee that someone isn't yandere tell clearly that you half-vouch or 90% vouch for someone.

When there are more than 1 yandere, make sure that those yanderes aren't fake vouching each other.

See also: http://en.wiktionary.org/wiki/vouch