Looks like you have quite a few similar vaults in play - so I thought I'd try a wildcard entry. It does, I believe, hit a large majority of the sliders,as well as the top 3 objectives. I thought a hand-drawn vault might garner more trust/affinity because you can tell that the company behind it is also human. No hard edges. Kinda humble. Human-friendly.
Of course, it doesn't really match the feel of the icon you uploaded...but, I thought it worth a try.