The Danton pistol was made by Gabilondo & Cia., the same company that later made the Llama line of pistols and revolvers. They were moderately well made guns, a cut above most of the similar Spanish pistols of the period. If in good condition, it should be safe to fire. Value is low, even in good condtion; those, or guns like them, sell for around $150 tops, and usually go for around $75, assuming they are fully functional, which many are not.
Those guns were imported in quantity before and after WWI. They were not military guns, even though some soldier of some army might have carried one as a personal weapon. Absent documentary proof, any connection with anyone's military service would be speculative.