Adding new Weapon Properites to 5E

[SoloJoke]

How easy would it be to code in new weapon properties for 5E? Specifically the ones that have automated effects, like REROLL 2 or CRIT RANGE 19. Are these hard coded in a way that it would be particularly difficult to add them? Or would creating similar properties be comparatively simple to code into a ruleset or extension?

[Zacchaeus]

You'd need to crack open the e5e ruleset and have a look. Then write an extension.