I am looking for a free of charge global or european dataset listing UXO presence or UXO incidents.
Here are some sources.
Zetica supplies risk maps for free for the UK.
OrdTek and EMODnet have water mine maps for a few European countries.
Propublica has performed a freedom of information request to get data that includes discarded munitions and explosives, which is available for download.
Australia has a UXO map.