if the jews had more guns they would have been able to kill more S.S. or brownshirts - demoralizing them and possibly reducing their numbers so they could have been kept at bay.
That's not a very logical presumption. It only works if you assume that the Nazis would not alter their strategy accordingly.
If the Jews has been more heavily armed, the Nazis would have appropriately escalated their response to compensate for this enhanced armed resistance. Sure, more Nazis might be killed in this scenario but more Jews (and bystanders caught in the crossfire) would be killed in running battles. Also, if the Jews (and by extension, civilians in general) had been better armed, there would have been more deaths and injuries due to gun-misuse before the war even began.