I agree most of what you wrote but one a few things, Luffy is barely bringing anything new to the table besides just the obvious stuff... something new to me would be a changing of his fighting style a little bit or tweaked with an added weapon or something. Luffy while getting new things still feels pretty stale. In fact all the Strawhats feel stale.
1- Marco shows up in the war
2- After war, Luffy takes Marco to drop him on WB territory
3- Marco tells him that WB and Ace grave is in that island, so Luffy goes visit the graves to pay respect
4- Luffy sees Ace's dagger, and takes it as a memento, and it becomes his actualy weapon... dagger suits him 100 times than anything else, simce he's close range combatant, also with awakening, he can stretch his dagger, and do lots of cool stuff with it
But I agree on weapons thingy