I've already voted for brass so please don't count this as another vote.

As I noted when I voted, I usually prefer nickel silver hardware. Easier to clean, less maintenance, and I like the contrast that its lighter/more neutral color provides, especially when paired with darker handle material.

Given the deep golden color of the Amboyna, however, it is my humble opinion that a brass single hilt with brass and black spacers (4th option) and a matching brass butt cap (5th option if I counted correctly) is the way we should finish this knife.

Why?

First, I don't see this knife as a user. These forum build knives are really cool and 'unique' (especially so for these with CW from Blade; Thanks Capt.!), and I don't think that I could bring myself to use one of them. If I did see it as a user, I would've voted for a NS hilt, and would endorse thumb notches or a thong hole for the fifth and final option.

Second, the brass at front and rear would enhance (as Tony pointed out earlier) and perfectly complement the beauty of the Amboyna, and the knife would, overall, be more aesthetically balanced and pleasing.

Third (and final), I showed my wife the photo of the Amboyna, and she fully endorses my 'brass design' as outlined above. It's OK to laugh at that, but: 1) she owns a ceramic/glass studio and spends a good chunk of her time designing color schemes for folks to paint; and, much more importantly, 2) if I end up winning the drawing for the knife, there will be no need for me to have to justify spending the money on "another" RMK (and those of you married for many years can well understand how beneficial that can be!).

Does adoption of the 'brass design' mean that we end up with a "safe queen"? Probably so, but a safe queen of surpassing beauty that would demand to be put on display.