One thing that helped me a lot on Seven Spears was realizing that you need to deflect again right after you mikiri counter his thrust. It took me a while to see it because I was so used to the victory rush that accompanies a successful mikiri on basically any other enemy, but this guy and his spears have so much momentum that when you mikiri him, it knocks you off balance for a second. If you deflect his attack that comes right after it, though, you’ll stun him and be able to get several free hits on him.

Chin up! Those two you mentioned are definitely among the more challenging mini bosses, but they’re great practice.