Seiga's hair stick is actually a "Wall-Removing Chisel" that lets her pass through walls. It is likely based on a chisel-shaped magical digging tool that appeared in Liao Zhai Zhi Yi. ([1]) In the original text, it was called 镵 (simplified) or 鑱 (traditional). It means a type of ancient spade or a herb digging tool. (See also the baidu pedia)
