The Angel Halo is a special weapon wielded by Luka, replacing his Iron Sword (although he still keeps his former weapon). It is extremely grotesque-looking, and as Luka puts it, "looks like [the angels] are being molested". It was given to him by Alice, noticing he has problems fighting to his fullest. The blade was created with 666 melted angels, and has the power to seal creatures (for example, an Earthworm Girl twirls into a normal earthworm, a human turns into a scarecrow, an Elf shrinks, etc.). For some reason, it makes eerie noises, which Alice says is expected.
According to Lilith & Lilim, Heinrich was the Angel Halo's previous wielder and sealed them with it.
When Luka reached Sabasa, a guard noticed his sword. Luka immediately assumes that the sword just got him into trouble, although the guard assures it isn't like that.
As Luka nears the Criminal's Jail, the Angel Halo suddenly shines with light.