You can use duck tape to attach more shields to the daggers. Secondly, you should actually only use one dagger, since your damage comes from getting kills you barely get any additional damage from the other daggers. It might be to late to fix that though. Just duct tape more shields to the daggers.
each shield will cause connected weapons to make a weapon attack one more time, if you have 8 shields touching a weapon through duct tape and a pavis then that weapon will do its damage 8 times, for the Assassin Dagger having multiple shields with duct tapes can get you to floors upward of 60 on its own, then it's just golden whetstones and Max health.