In the latest patch the shadow mundus got a nerf to 11% critical damage (and critical healing, which is a buff). Divines however got a buff to 9,1% 9,1% of 11% is almost exactly 1%. It very much seems that this is exactly why the change was made. Unfortunately the second piece of golded out divines gives no benefit towards the shadow mundus and it stays on 12%, and the full amount is 17% instead of 18%. Let's hope they either fix this or change it around so that the shadow doesn't lose 1% of crit damage/heal because of an integer mistake or something.