Johanna`s argument for leveling question

First I excuse myself for my bad english. I am french.

I plan to level next season a crusader and i plan to gamble the guard of Johanna and gabriel vambrace. I would like to upgrade a yellow 1h flail to get Johann`s argument and i saw i can get it at level 1 on diablo3 planer. My question is do i have to make a level 15 yellow weapon to be sure to get it or i can do a level 70 yellow and be sure to get it. If i do a level 70 yellow, will it be any 1h flail? Thx in advance for answer.

You can get it at level 1 via Blood Shards if you do the challenge rift right after the season opens. It is usually better to gamble armor pieces with shards since they cost 25 each instead of the 75 for a weapon so you get more chances. If you are extremely lucky and get the bracers and the shield then feel free to try for the weapon but it is a lot of shards to do it. With the challenge rift you can upgrade 1 rare to legendary once you acquire Kanai’s Cube since you get 35 DB’s and you need a couple to rank your blacksmith to max so that you can craft level 70 items at level 1. If you upgrade a level 70 rare to legendary then you can get any item for that upgrade since the Hope of Cain recipe in the cube is not affected by your character level. The Hope of Cain recipe requires a level 70 item to upgrade so you are unable to upgrade a level 15 for a chance at the weapon.