Have her passive shield toss bounce off targets that die before it reaches them, back to her to proc the shield. It's more a QoL change since lag and changing minion aggro can make last hitting with the shield unwieldy, but it might still count.
If you're talking at least Xin Zhao level reworks, some actual sustain would be nice for laning. She's simultaneously really mana hungry while having no way to regain life, where most tanks seem to have an innate sustain mechanic.
has his passive shield which remains indefinitely until broken apart

all have healing built into their kits (Gnar indirectly through his insane health regen and mega-gnar)
has infinitely stacking health
passive gives her almost infinite effective health going into engagements
uses energy as an effectively endless resource
can build health or mana on-the-spot
are the only tanks without this trait for laning, and of them only Galio and Poppy are regularly played as solo laners.
She has her passive shield, but it's only temporary, and from its changes around the time of Courage of the Colossus (which has since been removed), is very, VERY temporary, besides being difficult to proc and relient on sometimes inconsistent last hitting.
She certainly gets tanky once she has several items because of her W passive, but it can be an absolute pain getting to that point when she's so fragile early while simultaneously having no way to reliably get back into the game.