When Dexter is staging the scene to fake Travis's murder as ritual suicide, the knife changes from Dexter's knife to the ancient sword then back to the knife. Dexter then removes the knife and inserts the sword.
The name Kaja is absolutely abnormal for Ukrainian woman. It may be Katya but not Kaja.
When Deb asks Masuka if someone can kill themselves with a sword, he responds affirmatively noting the act of Hari Kari, or Seppuku. The Japanese act is performed by disemboweling one's self rather than stabbing the chest, however.
When asked if it's possible to commit suicide with a sword, Masuka says many of his (Japanese) predecessors have done it. Contrary to common misconception, seppuku is not a suicide. It's an execution. Yes, the subject cuts his stomach with a (much shorter) sword, but then the second person kills him by cutting off his head with the long katana. Not to mention, no self-respecting Japanese would call seppuku the vulgar word "harakiri".