The way it will work is that once an adventurer gets three cursed items of a specific set, her class changes. With the bondage items, the class changes to prisoner. Each class has its own weapon(s) and attacks, since the prisoner doesn't have her hands free, none of her attacks require her hands (in fact, none of her attacks exist yet, so I'll be taking your ideas into account for the moveset). Of course, she'll still get experience in that class using development goals which gives her better skills. And the idea of the class is also to be a tank as you mentioned.
Hopefully I found something you have not seen before, even though I think that is a bit unlikely.
It indeed unlikely, I'm a big fan of cursed equipment. The problem is that many of the images are hard to implement in a game without making it unplayable, buffing and tanking being the main exception.