Keep a supply of eye drops on hand and look for helmets that have the blind immunity. Basically just be sure to check the map before you start it; if there's enemies with blind, prepare accordingly. Same thing goes for every other status ailment (though frozen is tough to deal with as only one class can cure that).

As for the helmets, always be on the lookout for those in the shop, especially if you're using a dodge build (blind completely shuts down dodge builds so I'd say they are a necessity).

thanks !

Another way to deal with Blind-inflicting enemies is to have a unit that does not depend on accuracy to tank a hit during enemy phase and kill the unit on your next turn. Units that rely primarily on Mental attacks (e.g. Mentalist) or units that typically do not depend on attacks to be useful (e.g. Psy Shielder, Gasul, Engineer) can afford to be blinded to bait the enemy in, assuming they can eat the hit of course. You could also try to have a unit with higher Light resistance to try to tank the hit and try to resist the Blind infliction, or position them in a way where the enemy will want to prioritize another attack for higher damage without the chance for them to inflict Blind (e.g. a Photokineticist should want to use Mind Blast over Light Blast should Mind Blast do more damage, same deal with Golden Spriggats wanting to use Claw over Light Breath). Finally, there's the tried-and-true method of simply killing the enemy before they have a chance to attack with a Blind-afflicting skill in the first place, though this may start becoming trickier to do as the game goes on, particularly once you hit Gharial League and enemy Spriggats become much more common.

I like to kill, most necisists die with one or two shots from the crossbow.