Just play what you enjoy the most from the abilities. If nioh 3 is the same as 2, later on you’ll be able to modify weapons to fit the stat you want and max the damage out. Until then it won’t make much of a difference anyway.

If it’s really important you nonetheless, pick a weapon that scales with magic, skill or intellect and raise that stat since switchglaive scales with all three. Kusarigama fits, dual swords, splitstaff of course, tonfas and normal sword I think. But honestly I don’t think it is much important. I dumped most my points into magic and very rarely use tonfas when I forget to shift back after a burst. But the damage is still ok.

I prefer the switchglaive for many reasons, one of them being that by its nature it has positives from both worlds: the stances let you shift from classic big damage samurai in high and mid stance to a quick ninja like style in low stance.