All I have to say is that my baby sister has that same aspect in her chart and she is a bitch. She's very irritable and if someone tries to question her and she knows that she's wrong, HER MOUTH OPENS WITH AGGRESSION AND RUDENESS!

I am an Aries Sun Moon with Libra Mars.

It means a few things;

First of all it means your agression, assertiveness, and the way in which you fight is colored by Libra. So you have your conflict management esentially concerned with Fairness, justice , balance, and beauty. What house it falls into says the story about what part of your life is affected. Depending on how tight of an angle the opposition is will make the opposition effect stronger or softer (the "rude" part the previous response notes) The tighter the opposition, the more hidden your subconscious agenda can become. (and the more locked up in choosing the native becomes)

I have a boon of relief by having my conscious and subconsious minds (sun and moon both aries) being tightly aligned, so for me, it is all revealed and I may be locked up with the opposition, but I know consciously what lurks beneath. So I get some of the opposition mitigated.... yet not really because Aries rules mars and with mars in its opposite sign, it actually makes you "less" assertive" and prone to hesitation; especially an aries person.
I hesitate alot.

So, when you have a "big fight" pending, and you are hesitating, or when you find someone really hot and you want them, and you hesitate... this is your libra mars shining into your subconscious mind demanding you to be fair, just, balanced and beautiful.

what about fire and fire-mars leo?

I have moon in aries being the opposing midpoint of an otherwise wide saturn/mars in libra conjunction.

Yes, it can be hard expressing anger most of the time. But if one takes a backseat and look at why one is angry in the first place, the source of unhappiness can be identified quite easily with time and practise. Of course, by addressing the trivial matters that annoy the sensitive arien moon before deciding on acting out the anger will somehow help with the untimely outburst. When I get hurt or angry, i usually retreat into solitude and reflect on the events before I decided if there is any action to be taken. I also find that once I'm physically away from the source of conflict, e.g., the person or place that has made me angry, i'll feel much calmer and think more objectively. It took a long time but I forced myself to learn how to verberlise (calmly and rationally) my anger/frustration to the person involved. Otherwise it turns into passive aggression.

Breathe and wait for the anger to pass. then address the source of the hurt. don't lie to youself though. despite the arien/libran quest for integrity, we often expect honesty from others to us but not from ourselves as sometimes there is just too much pride that prevents us from admitting that we were rash, vulnerable or even selfish. It is not an easy balance and I still falter all the time but i guess we just need to keep trying.