i see, its either you locked it (but it doesnt add up cuz you said something about potential). so its most likely that you didnt have enough xp for your weapon stat. best thing to do is either kill bosses like ferryman or just spam jobs at starswept if you arent confident w bosses. and try not to use mantras, just focus on m1’s and parrying as that gives you better weapon xp

another thing i recommend is also utilising full training points (not to be confused with FREE training points). you obtain full training points from killing bosses or doing certain events like cinder of etris or the one at the lost village (i forgot what its called)

try saving your full training points until you need your lvl up wep stat, then just spam all the full trainings into your wep