This large keris, and the one owned by Pak Dibia are from Madura. Madura is part of east Java, but culture is different. Wanita di Madura have special reputasi!
I do not know much about culture Madura to be able to say what kind of ceremony they are for. I have also heard of keris like this made for special exhibition by famous Empu as demonstation of skill. Some man of power and money want to have one to symbol his power and money.
This one I gave my son is very good. Just like normal good keris, just much bigger. I think this one is only 100 years old.