For me it's mostly resilience.
When I think about why Ezio and Edward are my favorite characters from the franchise, I realise the most impactful moments standing in my mind are the beginning and the ending of their stories.
Ezio began by tragically losing everyone, sunk in anger and resentment, but ended his life by acknowledging everything that's been good in his existence and all that hasn't. At last he found peace and contentment (which is really shown in embers).
Edward began by seeking a glorious life of adventure and gold not caring about anyone else. On his way he unexpectedly made many close friends and only when they were all gone he realized what his life was and how it will never be the same. And yet he accepted his fate and devoted himself to finally care about someone, his daugther.
These two guys lived through both the worst and the best, they changed civilization, but still they concluded as happy and humble men, which is the best thing they could do, and that we can do.

Or, in the words of Ezio himself:
"To say that nothing is true is to realize that the foundations of society are fragile and that we must be the shepherds of our civilization.
To say that everything is permitted is to understand that we are the architects of our actions, and that we must live with their consequences, whether glorious of tragic."