To kill the Night Lights, you should avoid hitting the abdomen at all cost. Aim for the head, and try to hit them with a slashing motion rather than hitting them straight, damaging the abdomen trough their head. You can kill them by hitting the abdomen without explosion if you are careful, but this is more difficult and dangerous.
For explosives in general, you should be gentle if you want to deflect them or send them back. Don't hit at full speed and straight on, rather try to make them rebound on you blade or catch them in a flail before flinging them away. Explosives can explode before the end of their time if hit too hard.