Why would the SAMURAI reverse the lead hand on a SPEAR?

A Samurai manuscript talks about reversing the lead hand on the spear (Antony Cummins' video:    • YARI - A SECRET way of Holding A Japanese ...   ), but why would you do this? ▼3 extra EXCLUSIVE videos each month on PATREON, which make this channel possible:   / scholagladiatoria   ▼Facebook & Twitter updates, info, memes and fun:   / historicalfencing     / scholagladiato1   ▼Schola Gladiatoria HEMA - sword fighting classes in the UK: https://www.swordfightinglondon.com ▼Matt Easton's website & Pinterest: https://www.matt-easton.co.uk/ https://www.pinterest.co.uk/matt_east... ▼Easton Antique Arms - antique swords for sale: https://www.antique-swords.co.uk #history #samurai #spear