armed to the teeth

[CyMonk]

i have all weapons upgraded to 9. what am i missing? how do i get this achievement?

[7_of_9]

If memory serves well, you have to play all "weapon-challenges" too

[iLL357]

Mine popped up after finishing a marathon, which I did on the first place lol

[EXPERIMENTONGOD]

The workaround for this bug is completing more challenges until it pops up. Really weird but it works.

[Luko]

confirmed: race all weapon related challenges (after upgrading all) and you will obtain it then