oil of ghost touch?

[zauriel56]

is there one or am i forced to use ghost salt blanches for 1 hit or 10 arrows?

[avr]

There are spells which create weapons made out of force, which does full damage to incorporeal creatures - instant weapon, force sword, ghost whip. Maybe you could base something off this?

[zauriel56]

found spirit bound blade, a spiritualist spell, that gives ghost touch and one other of a choice of enchantments.