Absolutely not worth it, at least until there's a 5* Troika available and noone knows when that will be!

You might want to get an elemental or piercing weapon instead, you'll be glad to have both later when you make your first "full vulnerabilities set" (p.E.: attack beast & fiend with flourish or magnus, attack construct & undead with blizzbrand or voltech alchemer, attack jellies and gremlins with your faust. Or something like that). Getting a Khorovod first will push you one 4* (that later will be a dust-catcher) further away from that.

You don't need to upgrade it any further than kamarin then for that. Getting more 3* makes more sense most of the time than upgrading to 4/5* as long as you're staying in T2 (with the exception of bombs that get a bigger radius and some armor that gets better damage bonus or something, mostly all 5* equipment isn't better than 3* in T2 as the damage it does scales with the depth you're in).

( Attacking mobs almost exclusively with weapons they are vulnerable to makes a lot of sense in T2 too btw and choosing the right weapon for every situation is a big part of "getting better at playing")