In the live server, Pulsar increases the amount of max health it reduces from your enemy for each rank, from 10% to 13%. In 1.6, it is a flat 10%, and increasing rank only increases duration.

This is a deterrent from taking the morph, and most people already opt for Elemental ring over Pulsar.

Duration increase is useless because the situations where Pulsar is used is against trash pulls (only the tank or healer will opt for Pulsar instead of Elemental ring, to make the trash die faster to burst damage) where Impulse is generally spammed, and the fights take under 30s anyway, so the duration is kind of moot. If a fight is going to take more than 30s, it's better to use Elemental Ring anyway.

I don't know what it needs, maybe reduced cost per rank, but it needs something other than the duration increase per rank.