I don't know anything about the long blade, but can help you with the two Mark 2's
As you have noted the pics are not that great.... But it appears you have two Mark 2 knives? One with a bad handle and one with grease on the blade?
If that's correct, I don't know the mfg of the one with the bad handle because i can not blow up a clear enough picture of the ricasso to see if its marked there. If its not, then it should be guard marked. Looks like you have it matched with a fiberglass Mar2 scabbard. This should have a NORD (Navy ORDnance) number on the back. This is the navy contract number for the scabbard. This will tell you when the scabbard was made.
The other knife is a Ka-Bar branded USN MK2 as noted on the ricasso. Is that grease on the blade? Handle looks in good shape and it too is matched with a MK2 NORD scabbard. The Contract number on this one is 4723 and was the first contract for scabbards (~600k made from 11/43 to 7/44 for both the Mark 1 and Mark 2 knives).
The BM Co on the scabbard is for the Beckwith Mfg Company. They were a division of Victory Plastics... the VP mark you see on it. The 1/5 is just indicating the 5th run of that contract number.
So, this is a bit of history.
Yes, they have value. No, you will not retire from it...
the value is entirely dependent on the condition of the knives and scabbards and the mfg's. The pics make it very difficult to determine the overall condition accurately. But i can point out what i see good and what i see bad for each.
Lets start with the Ka-bar ricasso marked.
Good
per the pommel shape, appears to be an early made knife
Handle appears in tact
blade does not appear to be overly sharpened
blade is possibly black under the grease (orginal finish??)
Scabbard from pictures shown appears in good condition
Scabbard hanger looks like its all there and the snaps work
Bad
Guard is bent
grease, why?
Unknown
is the guard loose
is the handle leather loose
What color is the handle?
how is the pommel attached to the tang? (probably screw on or peened over tang)
are there any cracks in the scabbard?
Assuming the good is really good, the unknowns are good too and the little bad's remain the same, you can probably get $100-150 for it. Better pictures can help determine a better price.
The other one, unknown mfg
Good
per the pommel shape, appears to be an early knife, maybe
not much for the knife
possibly the scabbard
Bad
handle is broken
blade looks to be well used
guard is bent
guard is possibly loose
Handle is broken
Unknown is the scabbard
Probably a $75 package deal here. But depending on the mfg, this could be worth more (though i suspect its either a Ka-bar or a Camillus).
These being USN Mark 2 knives make them less valuable than their USMC counterparts. The scabbards on these are what really will drive the values, especially if both are Ka-bar or Camillus branded. We know the unknown branded one is not a PAL (no red spacers) and the pommel and handle cut don't appear to be a Robeson Shuredge so its pretty safe to assume its a Ka-bar or a Camillus. Neither of these brands are super valuable unless in excellent condition.
if you can, post better pics in better light that are closer up. can you wipe away a bit of the grease so we can see the color under the grease? maybe just better lighting can show that and you don't have to wipe away the grease.
you can always PM me if you have more questions or need anything else.