Leona's W (Eclipse) duration

Hi! Ive noticed it before and than found a video at youtube showing the same problem:

Leona's W (eclipse) says, at description, that the duration of the bonus mdef and armor should remain even after the explosion, right? (total of 6 seconds)... But look! Its just 3 seconds! After the BOOM, instead of keep the bonuses for more 3 secs as description says, it gets back to normal! D:

Shouldn't description matches with the gameplay? Seems there's something wrong here! ;c