Difficulties Justice presents certain difficulties and certain advantages when it comes to commentary. Justice also brings peace, although, as Saint Thomas explains, peace is indirectly the result of justice - in that justice removes the obstacles to peace.
Peace is the direct result of charity, for that is the virtue, which produces union of hearts.
Otherness Justice is done only in respect to other persons. A child could break another child's toy, and that would be a fault in justice if he failed to remedy the situation by buying another toy or fixing the broken one, for example. But if the child breaks his own toy, no injustice has occurred. Perhaps a fault against poverty is involved. This means that justice has to do not with a gift but with something which one owes.