Restoring an old breaking cimeter

[Ericfg]

Just got this, It's got a strange, sandy 'patina' on it. Khaki colored, not an orangey/rusty color. Cleaned western carbon blade for reference.

Some of the moderate pitting, and two spots of active rust:

I'm giving this a soak in white vinegar. This image after about 2 hours.

 

[Ericfg]

Soaking in the vinegar:

Removed after 2 hours and untouched:

After a moderate scrub with the nylon pad pictured:

The other side after a brief scrub:

 

[Ericfg]

The active rust spots before:

and after a 2 hour vinegar soak and brief scrub:

 

[Benuser]

Ever used phosphoric acid? Is what I use when I don't like a brown colour, or some superficial active rust is present. Turns it into a patina — sometimes boring grey, I must admit.

 

[Ericfg]

So earlier today right out of the vinegar. A nice, dark grey color:

Did some wet sanding. Started at 800 grit and that was not nearly coarse enough. So I went down in grits from 800 to 150, and then back up again.
Results (same reference blade as before):

The handle, after a light cleaning, now sits in a mineral oil bath that will extend overnight.
Note to self: even with moderate pitting start with 120 grit sandpaper.