Some stuff about fudo. that I posted elsewhere, but wanted to put it here too so there.
Fudo is one of the many names for the deity that started his buddhist life as Acala vidyaraja. Literally "the immovable wisdom king" as close as is meant. Fudo is the Japanese equivalent of Acala. It means literally "the immovable one" fudo is associated with various sects & buddhist groups across Asia by many names and incarnation/avatars including some quite bizarre forms with up to 1000 arms at least 3 heads and a variety of weapons. He also has quite a few secret names. It is customary in some buddhist practice to hide the intended meaning for some smaller rituals/mantras/mudras etc. Fudo, for instance, does not really represent violence. Purity, freedom from passions and delusions of life. He is a protector. In his right hand he holds Kurikara, Kurikara is an annoyingly complex piece of iconography if ever there was one. For one thing the name could mean many things "black dragon, black steel/metal" etc it is it is a vajra& vidya weapon vajra meaning literally "diamond/thunder" (fudo and many like him are associated with vajrayana Buddhism). Vidya meaning wisdom light knowledge etc.it's also a further embodiment of fudo and Kurikara the dragon. Who like fudo, is at once a separate entity and at one with the sword. He is often depicted trying to swallow the sword, the dragon that is, not fudo. The sword is used to destroy delusion and protect those on the path to enlightenment, as well as those on the vajrayana and various other "paths" and practices. The sword also symbolises wisdom in the dragon trying to swallow the sword, or occasionally itself. Signifying wisdom overcoming violence, aggression and/or passion. and that's just his right hand..