Right now on Kronos, 1H Weapon Spec improves the damage of MELEE attacks. So it works properly. But Seal of Righteousness, which should be considered a melee attack, is not currently considered a melee attack. I have pointed you to the issue and I told you what is required to see the issue fixed. Let me repost it again:
In which Clearly says: it increases damage done by Seal of Righteousness when you have a one handed weapon equipped as well.
What you just linked Theloras doesn't bring any new evidence.