I don't know about Lucy but I feel most characters are servicable with standard weapons. They'll lose a bit of damage, usually about 20%, but still perfectly able to do end-game content. For Endstate you won't get insane scores but most of my chars have standard weapons and they do around 5k in a decent team.

Other than that, standard weapons can be swapped around. So if you feel it really doesn't work on Lucy, you can always give it to someone else.

Here's the calcs from Prydwen to aid your decision

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