When facing many enemies that are grouped together, use Shizuka and equip Fleck. Then, run toward the enemies. Press Triangle while running. Try to hit an enemy with more health than the others. This attack deals damage but also plants a bomb on the enemy. Hit the enemy with any other attack to detonate the bomb. The explosion of the bomb does not hurt you.
Raffik.

When fighting a Juggernaut, use Benkei. Equip Benkei's club and hold Triangle until his club glows and sparks. Then, release Triangle and charge into the Juggernaut. Be careful not to press R1 before holding Triangle.
Raffik.

When in Kamui mode, press Circle if the "Circle" symbol appears instead of any other attack. This deals more damage. If the "Circle" symbol does not appear, then choose another button (for example, Triangle) and press Circle afterwards. This deals more damage.