[motan]

Hi Miguel,
I tend to agree with Ariel, but I will try to be more specific. The first two are original and old. I would say from 1930' to early 1950', although this is only an estimation. They do not belong to any specific type associated with the village of Majdal Shams, but could be made there. The scabbards, but also the blades are not of the Majdali type and look more like Syrian types, prehaps made in Damascus. Pictures 1 and 2 show the main types known to be made in Majdal Shams. Having said that, yours also do not look like later types made in Damascus.
My friend Mahmoud, who has many Majdali daggers, says that this older, but different type could be made in or around the town of AsSuweyda, a large Druze town in Jabal al Duruz (also known as Jabal al 'Arab) in the southern tip of Syria, but for now, this is only a hypothesis. Many of these daggers have been made and are still made in different parts of Syria, but also in Lebanon and Iraq (yes), and it is very difficult to pin down the exact origin. I am not even sure that the oldest type (pic 3) with the engraved copper plates really originates in Majdal Shams.
As for your third dagger, this is indeed a "presentation" piece made in Damascus. This type has been made for many decades for the tourist market and some even have "made in Syria" engraved on the blade. Always watch for the cast brass parts, especially the scabbard.