Manipulating objects,
possessing live creatures, (those without a soul are easier to posses)
Influencing phenomena in a small scale
Pyromancy
The power to banish all who he kills with his holy hook
Can see things that live people can not
Teleportation
Invisibility
Immortality
Indestructibility(as long as the attack or weapon doesn't affect souls or ghosts)
Can pass through objects

Powers(Nothing too overpowered please):
Manipulating objects,
possessing live creatures, (those without a soul are easier to posses)
Influencing phenomena in a small scale
Pyromancy
The power to banish all who he kills with his holy hook
Can see things that live people can not
Teleportation
Invisibility
Immortality
Indestructibility(as long as the attack or weapon doesn't affect souls or ghosts)
Can pass through objects

• Can pass through objects, power to banish those that he kills with his holy hook - If you're going to pick a fight against a demon or vampire and unleash your unbridled fury upon them without them even being to hit you, that'd be terribly unfair. My suggestion is that the character would have to possess a body first before being able to physically touch anything on the material plane. That way, he might not be able to teleport or become invisible while in this form, but he will still be able to use pyromancy and influence phenomena.
• Teleportation - There needs to be at least a cooldown time or limit for this ability. If you're going to get into any player-vs-player conflict, you would be able to fully capitalize on the ability, thus granting you the win immediately.
• Invisibility, Immortality, Indestructibility - "as long as the attack or weapon doesn't affect souls or ghosts"
  I'd be completely fine with that. Just don't go overboard
• Overall, your character is a ghost. Don't go around hitting people on the material plane while keeping yourself completely intangible.

Salt for example weakens them and they don't have infinite power themselves so they need rest after using enough energy and during that rest they can't manifest into the physical plane and their powers in general weaken.