Answer:
Curtail me thrice I am a youth; behead me once a snake; complete I'm often used in truth when certain steps you'd take.
I am a kind of coat that can only be put on when wet. What am I?
Skirts for men.
At night I come without being fetched, and by day I am lost without being stolen. What am I?
I am a box who holds keys but not locks. With the right combination I may unlock your soul
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?