The scene is inconsistent based on what we were shown in explicit writings. Here is why it was inconsistent. Other than the points i already mentioned, i have more canon evidence to suggest she was not combat oriented than you have that she was.
She was not in the first order.
As i already mentioned we get no info on her combat ability until the fight, such calibre of skill should have been atleast got a passing mention.
Several times, powerful fighters were needed but she wasn't there.
During the Lightning struck tower, when members of the order were guarding the school, Bill was there. If molly was so powerful, why didn't dumbledore bring her in too? She certainly would have been a huge help. She had great incentive to be there. Her son could be injured and did. Yet she wasn't there.
During the battle of Seven potters, when four of her sons, husband and daughter in law could be in mortal danger and when the order were so short on combat capable people that they had to bring in mundungus fletcher, she wasn't there. Four of her sons, her daughter in law and husband could die at once. Yet she chooses to stay at home?