What would joint legal entail exactly?

LoveyFNR

So STBXH contacted my lawyer after I was granted my OFP and said he would be willing to just sign the divorce agreement if some things were changed. I'm assuming he now realizes he doesn't have a chance to get what he wants anymore. He wants visits right off the bat (instead of restricted as we had put) which is fine with me as long as they are a continuance off the Order for Protection (4 hours of supervised each weekend).

He also requested joint legal custody. My lawyer thinks with the proof of abuse and X's horrible alcohol habit and criminal background he doesn't stand a chance for joint legal if we want to go for sole so my lawyer thinks we should still continue with going for sole physical and legal.

My question is what exactly does having joint legal give X the ability to do? I'm sure with how manipulative and coniving he is there could be something underlying that I'm not seeing. I'm obviously still going to fight for sole custody but I just want to know what I could be up against.