It seems that both in TFT1 and TFT2 the item Hand of Justice does not give the +40% attack damage or spell power.
Take any champion and put hand of Justice on it.
Watch the champion stats and see that Attack Damage and Spell power NEVER increase.
I played Zyra for 20 rounds like this, she NEVER gained any damage or spell power.
Although with 3x Hand of Justice she should have had increase in damage and spell power at any given moment.
If Hand of Justice has given the Heal option, then you do see the healthbar of the champion increase.
So that part seems to work.
But as soon as Hand of Justice should give attack damage and spell power then you see or notice nothing of that effect.