Nijuba and how it affects a sword

[jdawg221]

So I recently picked up a cheap daito that seemingly has nijuba. I understand that nijuba is typically seen on sanmai laminated blades, however something that confuses me is how it affects the durability of the blade and what nioi gire on such a sword would look like. For example, would it be nioi gire if the lower hamon runs off the edge, or if both the upper and lower hamon run off the edge? To add to this, is the upper hamon typically softer than the lower hamon, or are they usually around the same levels of hardness, just seperated by a line of either nioi or nie? Im guessing that most of the answers to my questions will involve "it depends". Regardless, any insight would be much appreciated. 

[jdawg221]

Also thought I'd post pics of the sword as it's the first sword I've encountered where I'm actually confused where the true hamon is. Is the darker banding closer to the ha the actual hamon, or is that just a visual difference caused by different steel composition?