How can I splice the tail of my tie and have it not look terrible?
You need to stiffen the fibres so that the thread does not tear though them while you are sewing. 

Clear nail polish

I ended up buying a small container and applied in all along the edges of the tie tail. About a 1/4 inch all around. 

After letting it dry it gave something for the thread to hold onto. Made it loads easier to get cleaner results.