Highlighted weapons are free options.
Xilonen's main job is to decrease Elemental Resistances of opponents using her Samplers. This, paired alongside the ability to hold (4), makes her a great asset to many teams.
Xilonen's Burst will heal the active character at intervals if 2 or more of her Samplers had their elemental types changed. Otherwise, she will deal additional instances of Geo DMG.
The resistance shredding from the Samplers occurs when Xilonen is paired with 2+ PHEC (Pyro/Hydro/Electro/Cryo) members. To activate them, press Skill, and continuously Normal Attack until her Nightsoul Points are full. This takes 2 or 3 Normal Attacks to do.
At [C2], Xilonen's Geo Samplers are always active, enabling her to be added in teams with 2 or more Geo members already present.
Weapon options below do not really affect Xilonen's performance as a Support.
If you do not need Xilonen's healing ability and are not using , her artifact stats do not matter.