Dictum meum pactum : goodness and wisdom Byron revised over days (2,4,2,2,4)

'dictum meum pactum' is the definition.
(Latin/English equivalents)

'goodness and wisdom byron revised over days' is the wordplay.
'goodness' becomes 'my' (both are exclamations of surprise).
'and' is a charade indicator (letters next to each other).
'revised' is an anagram indicator.
'over' says to put letters next to each other.
'days' becomes 'd' (abbreviation for days).
'wisdom'+'byron'='wisdombyron'
'wisdombyron' anagrammed gives 'wordismybon'.
'my'+'wordismybon'+'d'='MY WORD IS MY BOND'