I was thinking about how difficult it would be for this Paul to gather particular emotions without compromising his moral code:
RAGE: Pretty easy, especially in a combat scenario.
AVARICE: As shown in the update, easy to get from sadists, rapists, and cannibals.
FEAR: Again, hilariously easy. They're trying to kill something with the strength of a corpse-demon that can't die to anything other than White Light or running out of ring charge. On the other hand, intense fear (especially when you haven't felt it for so long) is not the kind of thing you want to start feeling in the middle of battle.
WILL: Probably can get from more experienced, focused combatants. The downside being that in Sunnydale, there's only so many corpse-demons that have lived long enough to control themselves.
HOPE: This could be tricky. Maybe playing dead, letting them think they've killed him, and then surprise-attacking them before their hope turns into aggravation, fear, or resolve. Less likely to work on smarter or more experienced combatants.
COMPASSION: ...yeah, I've got nothing. The type of people capable of feeling compassion strongly enough to gather charge from are usually either people who don't deserve to die, or can possibly be talked around. Fortunately for Paul, his natural desires (THE UNIVERSE IS WRONG WRONG WRONG I WILL MAKE IT RIGHT) can sub for this.
LOVE: As the Zamorans demonstrate, there plenty of people capable of feeling love who are also horrible wastes of space. Easier to gather from ambush tactics, for it takes a very unusual type of person indeed to feel love on the battlefield.
LIFE: This could be tricky. And possibly lethal. The exact mechanics of how Black Light and White Light interact are nebulous, as Death/Silence can feed on Life, but Life is also the sole weakness of Death/Silence. Assuming that attempting to harvest this WON'T kill him, there's still three obstacles:
1. Finding a person who appreciates Life in all of its glory, and is feeling it long enough for him to get there and rip out their heart.
2. Finding a person who appreciates Life in all of its glory, and also deserves to die.
3. Even if he can harvest White Light safely, I'm not sure that FEELING it would be.