GenericUser42800

I'm answering my own question, and hopefully it'll help someone else later. You can't use the chromablaster unless/until you reach level 10 and choose Vandal. Despite giving you starter equipment that implies you could use it, and even replacing it before you can, it seems that you can't until then (at which point it gets replaced again anyway).

I'm sure it's something I've overlooked, but I started playing a Muse and I noticed I have two sets of abilities based on weapon I'm holding. Harp and Chromablaster. Until I'm holding a weapon, hovering over each ability will show in red "Available when equipping {weapon}." If I equip the Harp, the text is no longer red and the abilities that require the Harp are available. If I equip a Chromablaster, the text remains red and I cannot use any abilities (and I appear to be holding nothing - I can only fight with fists / autoattack). Under Passive skills I do have both Basic Harp and Chroma