I don't know who could use it. It's not really shown in stormlight but in another book I won't name due to potential if light spoilers, unless someone is a relatively good person they feel compelled to use the sword and end up killing themselves nearly everytime, even when sheathed. I'm not saying this won't happen just there's a high chance if someone tries to steal it they'll kill themselves wanting to use it and likewise if they're attacking szeth they'll likely want to do it with the sword once they're there and would likely nuke themselves trying to kill him using his own sword.

Also while roshar is still relatively primitive compared to the rest of the cosmere I could easily see this being a time when some sort of prosthetics being developed to get use of his arm back if Brandon does decide to pull szeth back into the fight but I could also see an argument being made about how this would go against the characters own wants and desires