Yes... Assad's forces have Grad and other multi-barrel rocket launchers, and they are also using barrel bombs. But what about the rebels? They are also armed with sophisticated weaponry such as advanced anti-tank missiles.
It's a complex conflict, FSA, al nusra and ISIL are mainly a lot of local militia associated with low central control. For sure some are criminal but some are just citizen who want protect their neighborhood. I'm sure there is few real Islam extremist but people ally with ISIL and al-nusra cause they don't want be killed by them.