On iOS7, Apple introduced two new properties to UINavigationBar, 'backIndicatorTransitionMaskImage' and 'backIndicatorImage'.
By simply calling once:
[[UINavigationBar appearance] setBackIndicatorImage:[UIImage imageNamed:@"your_image"]];
[[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:[UIImage imageNamed:@"your_image_mask"]];
It will render a custom image instead of the default chevron glyph, inheriting the keyWindow's tint color.
And for removing the title, I'll suggest Kamaros's answer. Remember to call this code on the view controller that's pushing your new view controller. Removing the title text of an iOS UIBarButtonItem