Assassin's Creed Shadows allows players to unlock various abilities that suit their playstyle. While most of Naoe's abilities are focused on stealth and tools, Yasuke's abilities are more combat-oriented since he can wield a variety of weapons. Before you decide to invest in a particular skill tree for Yasuke, you should try out all the weapons available to him first. Once you've decided on a weapon that suits your playstyle, only then invest the mastery points in that weapon's particular skill tree to unlock the best abilities early for Yasuke.