Chigoes attack is broken but has been declared not a bug even though it clearly is broken. Certainly provides a significant loss of game enjoyment to have 40 att at lvl 60. I suggest you actually consider it a bug and fix it
Again, it isn't a bug. Chigoe gives up some atk in order to hit faster.

If your atk is that low at 60, you're not putting on enough atk instincts.