D.Gray-man, RustBlaster Recommendations
Both have a boy who is an weapon : Allen for DGM and Kei for RB, they are a white hair.
Ambiance are sames : dark.
Sames adventures with mechanic's failures...
Most of the similarities are in the characters. Rustblaster is all vampires, save for one person, and there's a vampire in D.Gray-man. There are many character similarities: Allen (DGM) and Aldread (RB), Komui (DGM) and Sakihito (RB), and Fou (DGM) and Kodachi (RB), just to name a few. Other similarities are with the feel and flow of each manga.