I started making Koryu Bokken, at the request of Holland guy who practice Katori Shinto Ryu, by his words, one of the oldest schools of Kenjutsu in Japan
first Sugino Sensei Dojo
this daisho was make from European oak,
Daisho was treated with red oil, until it reached the reddish color of wood, similar to Japanese red oak
next is Otake Sensei Dojo
also European oak but oiled with regular oil,
that would retain the natural color