Von leon equipments

If you need the gear from von Leon to beat Zakum and Hilla, you won't be able to solo von Leon, that's for sure.
Doing it on another character is also out of the question since you'd need to use scissors on the pieces to trade, which makes it extremely not worth it.

I think you'd be way better of getting a lvl 100 Tempest set from the Tempest shop, if you have that event now (or soon). If you get a full set you could trade out the weapon for a higher lvl one since there is 1 piece more han needed available. The Tempest weapons come at epic on reveal though.

Getting a Tempest set is out of question (for now at least).

Plus, we don't even know if we will get Tempest set at all. MSEA nerfed these coins event everytime by increasing the price of those coin shop items, nerfing event quests that give coins (or we just don't get em at all), and lots of stuff gone missing from the shop. So we don't even know if we would be able to get the set despite farming it for the entire event duration using multiple characters.

Oh, if you have the time you probably want to aim at the Legendary High Knight set from Vampire Castle a.k.a Dark Kiddy Kiddy Raid which is in MSEA right now. That set gives 45 W.Atk and a lot of stats. Though if you sell all those crafting materials you would probably able to afford 1 or 2 Empress Weapon already.

Each piece of material worth 20m right now in Cassiopeia and it requires at least 1000. There's at least 20 bil there.