The Wind shop SR weapon is the only one that's even potentially useful (assault skill), and as I recall you can't max limit break even a single copy. Daily disaster farming is the best way to strengthen your weapon arsenal outside of events. Starting your own 20AP fight and soloing it results in a far higher drop rate than joining the raids of others. In any 3-month cycle, the number of SR+ weapons you can collect from events is limited. Supplementing with Disaster farming is essential if you want to reach your team's potential in a reasonable timeframe.