That got nothing to do with missing weapons you will never have a chance to get again just to open some chests that got megalame low chances to give you some troops (totally random so can aswell happen you get a totally useless mythic).
Tomoz for example there’s a delve event, dunno which faction, but for example if it’s All seeing eye you can get for some hundreds gems the jar of eyes that’s a great weapon (think there should be the option to craft it too but dunno what it require).
But let’s take this week weapon from invasion, if you dont get it this week is lost forever, even more cuz you arent planning to cs no? and the few times a useful old weapon was “back” it was for real money only.
Take a look at this, is just 1 of tons threads about old useful weapons that who missed cant get anymore.
Ps: about gw dunno which bracket you are but on low lvl bracket on pc i managed to do 30k+ as lvl 90 with troops lvl 13 or so untraited, just looping converters non stop, giant spider and green seer to be precise, and killing stuff with the skull falling that sooner or later match, defo you dont need mythics for low lvl gw (my team score was barely 4k but could kill 9k+ opponenets that way).