So I was leveling up in HoI and I came across this upgrade node for the dragonbone master, and questionned what the hell it meant. Turns out if you fight the two boneyard minibosses ( Lament bell and Bonehammer Doll) while you have Dragonbone Master as your active ability, at certain points in the fight you'll have a sort of quick time event where you can use the ability to stun and completly deplete the stance of the bosses to nothing, because your use the fact that both wield dragon bones against them, which can speed up the fight a bit. Also it's just kinda cool. But to be fair I'm not sure if it's a massive help, but I saw people struggling with the bosses and I thought I'd share. I checked and I don't think there was any point at which you could use it against the main story boss, so I think it's just those two.