[@BeautyoftheDark]
The artefacts that demons can be bound to can be most objects; so even a book or notepad ect, however it is better if they are bound to more stable/strong objects such as jewellery.
The reason only humans can preform the rituals is because the spell created to bind demons was created to imprison them by humans to areas ( like the house). Binding to objects was developed later by humans who wished to gain power from demons, by binding demons to an object the human has control to a certain degree, however demons still have autonomy over their choices ect.
Angels are only really summoned if a greater demons presence is found and since all of the demons bound to the house are lesser demons, their presence isn't noted or isn't a concern. 

I hope this helps x