Assassin's Blade and Slayer advanced talent (assassinate)

[Zuro Duskhair]

An Assassin's Blade specifically says it can be used by a Slayer if the Slayer studies its target for three rounds- however- the Slayer Advanced Talent Assassinate states that a Slayer only needs to study their opponent for 1 round before an attempt.

Which one wins out in this case?

[Dave Justus]

The dagger requires 3 rounds of study to activate regardless of how many rounds it takes for other abilities. You can use those same three rounds as study for a death attack, but if you only study for one round, the dagger's special abilities won't activate.