Mending is a cantrip not yet implemented so could be interesting to mend the flail.
Does 5e include some kind of item degradation/condition system then?
I had just recently elsewhere seen the armor condition states that RagnarokCzD mentioned. I honestly don't remember if/how older D&D handled condition/repairing.
Mainly based on the table. Just in general, if the DM said something was broken or dirty, it was broken or dirty. Mending typically is the answer to that. And being able to repair things in RP is actually pretty cool. On a RP level, it gives a good reason for player's to not have dents or knicks in their weapons and armor, it can be used to repair scavenged arrows for your archer friend, and allows you to do small interactions like repair a necklace as a gesture of good will.
In a videogame it'd likely have to be interpreted just a bit differently. How I'd implement it is give it a tag in conversations so a caster with mending can fix things sometimes and give it the ability to fix some broken things in the world, from worthless stuff like a broken bottle to more useful stuff like weapons or jewelry. I'd just make it a nice but not crazy cantrip to have, like how it is in Table Top DnD.
