I think there's several issues with Nascent Flash, but I think the most urgent one which needs to be addressed is the fact that you cannot target a non-party member playable character with it. That is, in a 24 man raid, or in a pvp raid where there are alliances, Nascent Flash will not work on a non party-member (i.e., a member of a different alliance group).
This restriction is frustrating, especially in Frontlines PvP, where there are no party members around (because they died for instance), and you unable to use Nascent Flash even though there are plenty of Alliance Members close by.
I wish it was possible to use the action without a target, but it looks like SE is trying to reduce self-sustain in order to promote the importance of healers.
But for the love of all that is holy, allow Nascent Flash to work on Alliance Members that are not party of one's own party.
It's difficult enough to have to target another person, then hit your burst actions, then switch back to the enemy as quickly as possible to take full advantage of the tiny Nascent Flash window, but to have it NOT work on Alliance Members is too much restriction. Maybe SE doesn't want multiple warriors stacking Nascent Flash on a single target? But they could just have the second Nascent Flash overwrite the first.
I haven't tested this, but I don't even know if Nascent Flash will work with another playable character period if that character is not part of your party. Say, a hunt group. You might need to party with that person first before Nascent Flash could work. This is so cumbersome!
Fix this. Please!