Use Shizuka and equip Fleck when facing many enemies that are grouped together. Then, run towards the enemies and press TRIANGLE while running. Try to hit an enemy with more health than the others. This attack inflicts 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 will not damage you.
Use Benkei when fighting a Juggernaut. Equip Benkei's club and hold Triangle until his club glows and sparks. Then, release TRIANGLE and charge the Juggernaut. Make sure that you do not press R1 before holding TRIANGLE.
While in Kamui mode, press CIRCLE if the "CIRCLE" symbol appears instead of any other attack. This will inflict more damage. If the "CIRCLE" symbol does not appear, then choose another button and press CIRCLE afterwards. This will inflict more damage.