Hi Serafim, thanks for the report!

Do you happen to have a save game with this issue happening? Bear in mind that the increase in attack doesn't change the colour of the "attack" number, but changes the number itself. for example, a Stalwarts lvl 1 without any particular equipment will have 27 attack, while a soul burned stalwart will have 36 attack. At least that's what I'm seeing on my end =)

Sorry, i delete this save. Maybe, in this save i did some tests, and im sure that atack is not up. I look to: crit atack/simple atack percent. More than ten battles showed that stats is not change.  But soul burned damage to my units increase with time.
Well, i can be wrong and this bug is only in one save, as example i saw another bug in next game it was bound with mezary quest line but disappeared in another games. So i create this topic to find out people with same problem 

Gotcha, don't worry about it, I'll run a few more tests to see if I can reproduce it on my end.

Thanks!