I know I had the quest to collect Charcoal for a long time so you might not be able to fight Akamekabes yet, but i'll list the locations I remember anyways:
Mount Kurama in Kyoto (I fought 1 right at the end as a party of 2 on Normal Mode)
Den of Needles in Sekigahara
Nether Sekigahara field
I think Cedar and Gingko spears are both level 1, one may be level 10, can't remember too well, but you can try farming Lotus Spoons from Swamp Stickys in Daiku Cave on the first field and you might run into one or both of the spears identifying. There are also Swamp Stickys in Seiryuu Grotto (but you identify level 19~ stuff there).
But if you get the Lotus Spoon before the spears I recall getting most of my junk weapons for quests from Onigashima Training Grounds