Yes, weapons in Devil Hunter can be traded between players, along with crafting materials, directly with anyone on the same server.

The difference between the Armory and the Black Market is that the Armory sells standard starter weapons openly, while the Black Market is a hidden shop unlocked through a quest chain, selling rare items and weapons not available anywhere else.

Unlocking a Hybrid form in Soul Realm is genuinely difficult, it requires a Hybrid Heart, which drops at roughly a 5% chance, plus completing three separate Soul Realm quests.

Yes, you keep the Weapons, Devil Flesh, and materials included with my purchase, exactly as shown in the listing.