It could be many things, some which we don't know about yet. In addition to this, it also a signal to the ML basically.…
In episode 1 when they 1rst meeting DX gives her his handkerchief to clean her hand because there is blood but she does nothing because she does not see the blood. also When the kills that woman, she does not react to the blood on her face In episode 7 I think. he again ask her to clean the blood that was on her face and hand.
It is a very old sword and the design fits jn my opinion.
I drop what I really do not like. For example I tried Love jn the cloud 3 times before I dropped.
Nice to see him here with Arthur again.