Why would that be a problem? It would make sense if they were both attacking at the same time for them to hit each other's swords. It could also make for some epic dog fights as the wanzers circle each other clashing with swords until one gets the right angle and hits while the other is unprepared.
There are several:
First, they are super small so there is a lot of chances they could miss each other a lot and be far less efficient that just shooting each other.
Second again they are very small so the damage dealt by the blade would be insignificant, if it registered at all.
Third, I doubt it would lead to sword dancing but rather to springy face to face jousting, a much less interesting spectacle.
Overall I'm really happy with the current system where they only attack ships with their blade. There is something exhilarating to see one of your Frost manage to dodge a Conquest fire and get close enough to slash through the whole ship's length along it's arm.
And thanks to everyone else, it was a very fun one to make!