Highlighted weapons are free options.
Xianyun's main utilities are her jump height boost, healing, and Plunging Attack buff. While her healing is tied to her Burst Levels, the only way to increase her Plunging Attack buff is by increasing her total ATK.
Most teams will not use all three uses of Xianyun's Skill, since it is too time intensive to do so. A simple is the ideal rotation for most teams.