Lol non of what you mentioned are inconsistent showings.
> What made you think Sengoku's punch could kill Luffy when Kizaru's kick couldn't kill Luffy?
> What made you think M1 couldn't block a slash from Mihawk when manga has stated that a swordsman must choose to cut something?
> What made you think Ace could when Ace stated that a fight between smoke and fire would be useless?
> This is not a powerscaling feat because there was no battle.
Powerscaling is down to knowledge of the material. Oda cares about narrative just as much as the power structures established. He can't magically make Nami block Hakai because "narrative"
> What made you think Sengoku's punch could kill Luffy when Kizaru's kick couldn't kill Luffy?
> What made you think M1 couldn't block a slash from Mihawk when manga has stated that a swordsman must choose to cut something?
> What made you think Ace could when Ace stated that a fight between smoke and fire would be useless?
> This is not a powerscaling feat because there was no battle.
Powerscaling is down to knowledge of the material. Oda cares about narrative just as much as the power structures established. He can't magically make Nami block Hakai because "narrative"
In the manga Ace just puts up a firewall and says “you can’t beat me.”