Arcadian anvengers primarily spawn in the lower Law quest levels. Primarily in the castle but also in the road leading to it, but rarely.
They always drop 2 blessed rustproof short swords on death, which are always at +0 or higher. The material varies, but most are made of iron. Regardless of what weapons they wield, they will deal passive holy damage which can be quite dangerous.
They are resistant against poison, petrification, slashing and piercing and weak to unholy. On death they will strengthen all living arcadian avengers on the level, making them more resilient and overall stronger.