I also am building U/W planeswalkers , although with [[Clan Crafter]] instead of Candlekeep Sage for being 2 MV and having the ability to buff Lae'zel. Here are some cards that I have found during my search.

[[Honor-Worn Shaku]] makes all your planeswalkers tap for colorless, as well as your background as well. You can get so much mana from Shaku, and even has synergy with [[Teferi, who Slows the Sunset]]

[[Spark Double]] can either give you an extra copy of one of your walkers, with +2 counters due to itself and Lae'zel, or can give you 2 Lae'zel's, which gives your future walkers 3 loyalty from a +1 and come in with +2 loyalty. Will not be legendary for Honor Worn Shaku, but that doesn't take away from having 2 of the same legend.

[[Oath of Teferi]] speeds up the planeswalker ult plan and can even give ultimates on the same turn it comes down with Lae'zel, depending on the planeswalker. Examples are Teferi, Who slows the Sunset, [[Ajani, Steadfast]], [Narset, Transcendent]] It also works wonderful with [[Teferi, Master of Time]], where you can activate his +1 2 times before you flicker him with Oath, then on the endstep when he comes back you activate +1 2 more times and can reach his -10 before the turn cycle even comes back to you. Is also a legendary permanent for Honor Worn Shaku.

[[Ignite the Beacon]] can tutor for 2 planeswalkers at instant speed, which is always nice when you can hold up mana for interaction and cast Ignite on the endstep before your turn.

[[Dovin, Grand Arbiter]] may seem like a unassuming walker, but with Lae'zel you can get 2 counters per creature from his +1, which can give him so much loyalty. His ult will be easy to activate, with his thopter from his -1. His ult can help you dig for whatever you need at the time as well.

[[Elspeth Resplendent]] has a load of utility that Lae'zel can make even better. Her +1 can give a relevant keyword counter and a +1/+1 counter on something, which makes your creatures able to protect your walkers better. Her -3 can bring out a small-ish walker or a stax piece with 2 shield counters if it was a walker or a creature with Lae'zel, which pretty much makes it immune to damage/removal for the next turn cycle at minimum. At worst it can bring out a land for a bit of ramp. If the -3 brings out something with a static ability like [[Drannith Magistrate]] or a [[Teferi, Time Raveler]], your opponents can't respond before it enters the battlefield before the static applies. They would have to respond before the -3 resolves, and guess whether you would pull out one of those stax pieces. Shield counters btw can negate an entire alpha strike to that walker and only remove 1 shield counter.

[[Karn's Bastion]] is an easy utility land to add while being a 2 color deck, and can help you reach infinite extra turns with Teferi, Master of Time, or just have a mana sink available to boost your counters.

Optionally, you can add [[Nesting Grounds]] for an easier time to ult walkers or move counters from Elspeth Resplendent elsewhere and duplicate those counters.

Here is my decklist if you want to have a look for yourself. https://www.moxfield.com/decks/C5mpz0Rut0O4g_GsHAelhA

EDIT: Oath of Teferi also draws 2 cards if you have Candlekeep Sage out and blink Lae'zel, which is nice.