Whilst Understand that it limits the use of it, it is still possible. As it stands at the moment lets say you were fighting Cardin, you hit his mace. He blocks your attack, now all you have to do is stay there and drain him dry. If he holds his block he loses, if he tries to attack you you can quickly strike him repeatedly still drawing aura from him and damaging his aura with conventional attacks. It's the same if you fought someone with a shield like Jaune if he blocks you, you could simply stay and drain him dry.
If you have to make contact with a person however its a bit more balanced. Take yang for example, she has to punch people to do any major damage. That means getting in close getting around weapons etc even if just for a moment. This would be the same, you'd have to get under their guard and then all you have to do is touch them. That's before considering the additional bonus that the healing gives you in a competitive setting, especially as no other character has any way to heal.