Leona's final Splash Art differs from that of her Art Spotlight with the main difference being her hair.
As a "Chosen of the Sun", and with sun-based powers, Leona may be a reference to the Solar Exalted from the Tabletop RPG Exalted.
Leona's dance is similar to the Force-Shielder Class skill called "Shield Break" from Cabal Online.
Leona's passive, Sunlight, is similar to Lux'sIllumination. The two differences are that Leona herself is unable to activate the mark while only Lux can activate Illumination, and that any damage from an ally can trigger Sunlight, while Lux can only trigger Illumination with an autoattack and her ultimate, Final Spark.
Since Pantheon's and her place of origin is based off of Ancient Greece, the Vergina Sun, a symbol unearthed in Ancient Macedonia may be the reason why her theme is the sun. In her work in progress poster, her shield has the complete Vergina Sun symbol with all 16 points, whereas in the classic skin, the Vergina Symbol on her shield appears to not have spikes on its bottom half.
It still has all 16 points but 5 of which are attached to the shield itself and not on the Vergina Symbol.
Valkyrie Leona is based off the valkyries, a host of female figures from Norse mythology who wander the battle fields retrieving slain warriors who are to be brought to Valhalla after a glorious death in battle. This is fitting as a skin for a true tank, who can to an extent decide who dies in battle by stunning key enemies and saving allies.
Leona's dress appears to become see through, showing her undergarments while hiding in the bushes in her Valkyrie skin - this is an unintentional graphical error. This due to the fact that the model has several layers and entering a brush causes the outer layer to become transparent.
Solar Flare leaves an imprint of the Iron Solari upon impact.
Eclipse makes the phoenix of her shield to open its wings trying to cover Leona's head.
The splash art has some ties to IronStylus, an avid Leona fan.
The overall avian theme to the skin and the scarlet macaws flying in the background pay tribute to IronStylus; he uses one of those birds as his avatar on the forums and he is a proud owner of similar birds.
The name of the skin shares its initials with his pseudonym.
Leona and Diana are adversaries, with Diana being the "Chosen of the Moon" and Leona being the "Chosen of the Sun".
The "Chosen of the Moon" and the "Chosen of the Sun" depicted in the mural are not Diana and Leona, but their ancient predecessors.
A post by IronStylus in the thread Diana's lore, Diana and Leona may share a bond between one another as more then the "Chosen of the Moon" and the "Chosen of the Sun". This can only be implied by the quote "We want them to be intertwined, and without delving too far into assumptions and implications, without getting too detailed about their past relationship, what is more tragic than to have to kill someone that you love?".