The Ascendant represents you on the physical level of your life, much as how the cusp of the second house can represent your possessions and wealth, the cusp of the third can represent your siblings and local area and communciation, and so forth. In this pattern, the Descendant or the cusp of House 7 (the house of the "other", the partner, the spouse, the client, the rival) represents the primary "opposition" in your life. I don't mean opposition in the terms of rivalry, but how you encounter other people on a one-to-one basis.
The Descendant can mark how other people interact with you personally, since the Ascendant is how you interact with the world and everyone else. It can be seen as a "highly sensitive relationship point" in that the sign that rules the Descendant (Leo, in your case) shows how people will show themselves to you. It defines the theme, if you will, of your relationships to others.
In your case, you have Leo setting. To be brief, see what people with Leo Rising have going on, and that's how people will act towards you and interact with you. Your relationships (partnerships business and romantic, rivalries, competitions, and so forth) will have qualities of Leo that offset your qualities of Aquarius.