I’m where the blade begins its bite, Where mountains taper into height. I’m also words that quietly slip, A hidden hint upon the lip. What am I?

You can sit on me, and ironically, I am a discrete word for what comes out of the part of your body with which you sit on me.

Portable minds that whisper with keys, their screens are windows to the world, connecting thoughts with a touch, they rest on your knees and travel with ease.

Change my first and I'm an enchanted drink. Change it again if you have no clue. Change it once more to move. Or keep me as is and I make your skin feel like new.

Underfoot, it's lucky and round, Keeps the horse's hoof safe and sound. A symbol of fortune, for those who believe, In the old country, it was nailed with reprieve.