If it's a good weapon, it's better to have multiple copies and brick them in the long-run.
If it's an ok weapon that you currently use, then maybe - I LB my light Tsuku bow when I got a dupe 'cos I currently use it to boost my hp without sacrificing too much assault. I have no intention of bricking it 'cos it's not worthy of bricking, but the extra stats are useful until I can find a replacement.
If it's a bad weapon, technically you should fodder it, but I usually just leave mine in gift box in case I ever try to build a phantom grid and am one weapon short or something like that.
EDIT:
Ninja-ed
2nd EDIT:
One thing worth pointing out - weapon FLBs often come out some time after the hime came out, so it is best to check the JP wiki to see if the weapon will get a good FLB in the future.





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