The Widsith is the best weapon I have for him. The ATK buff especially is awesome if you happen to get it. The EM is pretty meh, but still increases whatever swirls you happen to do. And even if you don't get the ATK buff it still gives you crit damage, which is always nice to have. If you want I can make pictures of my gears later when I'm at home.

As for a general text version to answer your question from above:

I always run Bennett with 4pc Noblesse + Sapwood Blade (or any other high ATK Sword in case you're good on ER). Crit, ATK and ER (as always only until you can burst off cooldown) substats are all valuable. For main stats I'm running mine with Crit/Pyro/ER, though you can also use ATK sands if you have enough ER without then.

For Layla 4pc Millelith with Favonius Sword is great imo - just make sure to give her enough Crit Rate. Mine is Crit rate/Cyro/HP for main stats as I want her to have a balance of shielding and personal damage. If you rather have her shield be more tanky you can also simply give her 3x HP main stats, as long as you make sure to get crit rate for the sword somewhere.

Since you don't really need the swirls with Wanderer as carry I'd just give Faruzan a 4pc Emblem to help with her high ER requirements at c0 and to also boost her burst's damage. I'd also give her a Favonius Bow. If you build your Layla more offensively you can also think about giving your Faruzan a 4pc Viridescent Venerer set and try to swirl cryo to improve Layla's damage even further.

You'll still need to invest heavily into your Wanderer though. The supports alone won't give you consistent 100k charged hits. Also c6 Faruzan helps, even though I definitely wouldn't recommend spending to get that.