You can create these items as many times as you like, on as many characters as you want. Both in pre and post. Each time you use the command, they are automatically customized to the character you are currently using.
Edit: just to clarify, you can not have more than one copy of each item on the same character. If they’re all in your bags, and you try and use the command again, an error message will show. However, if you accidentally delete one or more items, and use the command again, you will get a new copy of the missing items. This however only applies to each character, so you can have for example the imp on all of your characters at the same time.
I hope that was not too confusing 
Another note just in case you were not aware the Igneous Summoning Stone (Fire Imp), only works on chars less than level 20, but extremely helpful in Pre.
Ya thanks for the update guys, really appreciate it. I wanted the stone for my perma-pre char, but also wanted the bow to be tradable. Kind of at a delimma right now
If you don’t mind me asking, why do you want it to be tradable?
the /bonus is bound to your account,and only that account. You cant trade /bonus items to an alt account.
And if you want your alt account to have the/bonus you need to buy it on your alt account
The imp can only be used up to level 20 so lvl 1-19
And if you dont feel like paying for it then that is your problem, I want a unicorn,doesnt mean I will get it
One other note about the bonus items. You can create multiple copies of each item on each character by putting the item you want either in your Xunlai storage or equip on a hero.
As noted, however, they are still customized to that character and cannot be traded to other characters.
