Wielding heavy weapon offhand while attacking with one-hand primary weapon

I was searching rules for following scenario. Players play Dex fighter and uses finesse weapons. He is using disarming attack on enemy and collects its heavy weapon. While has less than 13 str he would have disadvantage on attack with heavy weapon. 

Logic says to me that wielding heavy weapon with that character should also apply disadvantage on attack with main hand finesse weapon as character needs to keep balance etc. 

I wasn't able to find any rules for such scenario (suppose it was not planned anywhere) and heavy property does not implicitly say that could affect attach with other have weapon (as heavy weapons are two-handed no one expect you have another weapon). And nothing prevents character to wield two heavy weapons (however you can't attach as you need to hands for that l

Maybe someone has similar question and found something more.

There's no rule about heavy weapons doing anything to the other hand, and you only need two hands while attacking with it. Technically, if there were a Heavy weapon without the Two-Handed property, it would restrict even less.