1.3 World PvP has been... interesting. It's good that Trion has moved PvP away from Zareph camping all day (though I do feel bad for the unwitting level 40s in Mage's Mark), but populations being what they are, its a bit zerg-or-be-zerged out there. With Condemned gone, its not so one-sided in favor of Guardians, even though they outnumber us by a good bit now.
After messing with various Assassin specs this week, I threw up a little in my mouth and decided NB is just more my style. I wish there was a viable NB spec for PvE, but Deadly Dance is just too good and has basically 0 synergy with NB, plus NB lacks the AP modifiers in BD and Asssassin. It's too much of a handicap. Maybe some day.
I've finally settled on Living Flame for PvP. I resisted it for a long time with my Nightblade Beast and Gunblade specs, but I love Nightblade and I think that despite how much I hate 51-pointers, it doesn't make much sense to go 44NB 16 Inf 6rng when I can go 51 NB 15 Inf 0 MM and only lose a snare and some AP, while gaining Living Flame.
I like 0 MM over 0 Ranger with NB because you already have a ranged finisher with Flame Thrust and Swift Shot is helpful in getting you back into range (or staying out of it).
The problem with this spec is it doesn't do too well against Assassins (at all) and struggles against Parry-gons and shield warriors as well. It is strong against mana bars and it will bring down a cleric solo. However, if a good 51sin opens on you, you are 50/50 at best, even with every cooldown up. With 600 valor, I have sins take me to 40% in 5 seconds then vanish and let me bleed.
Parry-gons you basically need to avoid DoTs and Dark Contain them when you see them start parrying every attack. If they have Break Free up, you'll need another CD, like Twilight Shelter. You can still sneak attacks in from behind, but Rift is not so good at detecting where you are in relation to the other player's orientation, so you can try, but they are mostly invincible.
I still keep Gunblade around also, because its the best overall. The kiting capability from Marksman gives you a strong chance to beat anyone. It's not as strong against bluebars but can still win, and Swift Shot/Hasty Departure/On the Double let you kite Assassins and warriors and win that battle.