Hello Sedy,
It's been a year and 2 months since Ishva updated, we have killed 55 world boss Ishva untill now.

these are the amounts of epic weapon with crit bonus stat that we have got,

staff: 1
rod: 3
gun: 4
daggers: 0
greatsword: 2
dualswords: 5
sword: 4
total: 19

Most of the time, the boss dropped 2 weapons because I used lucky loot charm.
Among more than 100 weapons, the ones with a crit bonus stat account for less than 1/5,
in the past a year we didn't even get a staff and daggers with crit bonus, based on this number, a lot of players have to wait for years to get that, I would say it's a bit too long, would you like to consider increasing the drop rate of those and maybe adding one more Ishva boss per week ?