Magic Weapons lose all of their magical properties and are treated as a mundane weapon of the same type while the models remain in base contact with the Lammasu (including the rider of the Lammasu itself).
Source: Warhammer Armies Project: Unofficial 9th Edition (v2.2)
Magic Weapons lose all of their magical properties and are treated as a mundane weapon of the same type while the models remain in base contact with the Lammasu (including the rider of the Lammasu itself).