Horseshoe crab blood is blue in colour, due to the presence of copper. It's valuable because it contains an "amebocyte" used in the field of biomedics to identify bacterial contamination in vaccines and all injectable drugs. The energy generator in this movie, the imorium clustergram, has the same blue color as the Horseshoe crab blood.
Characters on multiple occasions brandish a katana or sword and refer to it as a "ninja sword". Ninjas didn't use swords, samurai did.