SidusLupus said:
Detect Alignment/ Smite Alignment
Protection from Alignment
Holy/Unholy/Chaotic/Lawful weapons, ect.
If you completely got rid of alignment, then you may just consider to ban those spells and enchantments from the game.
If you instead dropped the
permanent alignment of characters, so that a player is not compelled to have a written alignment on her papers, but the concept is still somehow part of the game, I'd suggest that the DM bases alignment issues on the cuurent behaviour/intentions of characters.
For example, instead of having an "evil" individual, you regard everyone basically as neutral or alignment-less. If the person e.g. commits a murder, he may have now an evil aura around him, and the aura may even last years if he never atones or at least repent inside and try to make amend. The aura may also appear before the actual murder, originating from his inner desire to commit it while he's only planning it.
Some characters such as evil cultists who regularly perform human sacrifices, may effectively have a constant evil aura. But if they stopped
behaving evilly, then the aura may slowly fade.
It is more complicated (and slightly different) when it's about law & chaos, but e.g. a character currently enforcing the law may register as lawful for the moment, but not someone merely following a code of conduct. Someone would be momentarily chaotic if participating in an action against the current legitimate government for example, but not if he was just stealing something for himself.
IOW, I would adjudicate the good/evil axis when individual consequences are concerned, and the law/chaos when social consequences are concerned.
For weapon enchantments, you could also run it differently: instead of making a holy weapon work against evil, you can make it work
towards good, which is not the same thing. E.g. it would not work better when executing a serial killer when the killer is already imprisoned and not able to kill anyone anymore; it would work when attacking the killer actually
does good i.e. saves the life of an innocent currently threatened.