How do people honor the dead in this world?

Honoring the dead varies greatly by culture.
Warren, the guildmaster of the Users in Sedora, planted a tree to honor a subordinate that he lost. The Huntresses use resin harvested from a fallen Arkett tree to create coffins of crystal to preserve the bodies of their daughters. Some religious humans burn their dead so that their bodies may not become vessels for evil. Warriors are buried with their weapons, unless the weapons were given to another before they died. The caravan members bury their dead, but they make it a point to save a memento, perhaps something that belonged to the loved one, something small they can carry with them as they travel, so as to remember those they lost.
For the Arketts (see Arketts - Culture), death shouldn't be common. Yes, people die, mostly in the hunts for Shadows, but rarely elsewhere unless there's a bloody conflict between factions. When a death does occur, there is a single chamber on each island where they bury their dead, like a grand family crypt, each one buried beneath one of the Arkett's trees. Placed on the outside of each tomb is a holographic image of their individual scroll markings, the blue lines that appear on their skin only in the glow of Etherion light, as well as a summary of their life. That hologram is saved in a plaque and stored in the vault of the dead.