any D'art use tends to run with that weapon...
last i seen, her 30% debuffing comes from the HP ones (and you really would need a lot of HP to survive without a healer or with minimal healing).
not saying to prioritize andromeda's weapon over D'Art/Herc, but it's not a bad idea to get her weapon for when you lack a healer. if someone has Sol, then forget about andromeda's catastrophe weapons entirely as Sol should be enough to cover that spot until 2019 when thunder finally gets a really good healer...
it's more "get it at some point if you need it", not "get it ASAP"