Edge of pound coin assigned this, originally Latin as agreed? (5,2,7)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

written on the edge of a pound coin, apparently meaning ‘as agreed’ in Latin. Literally meaning ‘decoration and safeguard’, the inscription (decoration) on the edge of coins was originally to prevent obvious clipping, or removing metal from, the coin, thus devaluing it (safeguard).