15th century dagger with later blade

[Villerica]

I don't think that it is Saint Sebastian because the figure has wings if you look carefully. It might be Cupidon or mixture of Cupidon and Venus ?
The couple beneath are both wearing cotehardies with buttons .

For me the style of the gothic decoration seems 1400's rather than earlier or later. However the form of the dagger makes me think of the later Swiss daggers but I have very little knowledge in arms.