Comment 7 for bug 939020

its possible that its not keepass fault but some general problem when the desktop stuff gets updated.
Try installing and purging different packages that install into /usr/share/mime

dpkg -S /usr/share/mime give you a list of installed ones, on my system:
brasero-common, keepass2, apport, shared-mime-info, obconf, nautilus-data, libreoffice-common, opera, kile, gnash-common, software-properties-gtk, tomboy, kate-data, virtualbox-qt, monodevelop, vinagre, kde-runtime-data, grsync, kdelibs5-data, banshee: /usr/share/mime

updating the icons is done with sudo update-icon-caches /usr/share/icons/hicolor/