I won't delve into gear too much, but I will mention a few ancillary tidbits to keep in mind-
-food. The crepes are your best macc option and a real must for 135+content.
-job points. Are you 3 starred yet? Even with max job points it can be a struggle, without...forget it on some of those.
-vorseals. How many macc vorseals do you have active?
-support. You need a GEO to really have a chance at landing enfeebs on those targets.
-natural resistances. You're not going to ever land some spells on certain mobs. Ever. And that happens a lot in this level content.
All that being said, we still have to try! Chironic hose with their "Immunobreak +1" is a necessary piece. Some slots are obvious and haven't changed much (reforged empy body, reforged relic hat for example), Another interesting piece is the unity shield from aspid v2.
Some options are going to require defeating the content you're up against now.
Sometimes, you're just going to be spamming enfeebs thru Immunobreaks until it lands, like blinding Maju for example. And some days you'll swear the gamer us on easy mode as everything lands. It's the nature of enfeebling high tier content, and in reality it's always been this way (silencing Suzaku back in the day comes to mind). Control what you can (see above),gear for skill, macc,and MND,bring proper support, and hold on.