From Gregory's account we know that Leobardus came to Tours when, it seems, Gregory of Tours was already a bishop, and then lived in the cell near the monastery of Marmoutier for 22 years, until his death. Thus, Leobardus must have died not so long before Gregory himself did, in 594.
Sacerdos ("priest") indicates here most probably a presbyter. Cf. the record  where sacerdotis oratorium ("oratory of the priest") denotes a chapel of a presbyter.