I don't know how common they are but I would think that the quality of the blades would be inversely proportional to the number available; with numerous crappy ones and few good ones. Bernard Levine reports that in the 1970's a large number of small, badly worn krisses were dumped into the US market at relatively cheap prices. Yours does not appear to be one of those to me but, again, I am no expert on the subject.
The blades on your weapons have seen better days and need to be oiled at the very least. I don't know who could tell you what they are worth, but I would try to find out so that you can decide what to do with them. If they turn out to be valuable, it might pay to have a professional restore them for you. I learned the hard way that you shouldn't just put valuable antiques on a wire wheel and clean them up. (I also learned that your run of the mill antique dealers don't know much about old weapons, nor how to restore them.) Indiscriminate buffing, polishing, etc. can quickly ruin their value. Of course, if their value isn't important to you, have at them. If that facon is fitted in actual silver it would certainly be nice to see it cleaned up.
Good luck.