Markings on Crusader era sword blades - any info?

[monacoauctions]

Anybody out there with additional info' on the markings on the blades of these Crusader era swords ? Both are correct for the 1st Crusade and both blades are stamped "OS". An "O" and an "S" are thought to represent the prayer O Sancti which was a prayer written at the time of the first crusade to invoce strength and courage in those leaving for the east. It is documented that knights would undertake a 24 hour prayer vigil before depart repeating the crusaders' vows and prayers; it is also thought that weapons were blessed by high ranking clergy during this vigil. A number of theories have suggested that weapons were then marked with the "OS" to give them strength against the infadel.
I'm trying to find out exactly what the O Sancti prayer was as i can't find any exact reference to it, there are a few blades existant with this type of marking, all seem to be from the late C11-late 12th so the time frame is about right, i've found @ 10 other blades so far in various collections.
Both these swords are larger than normal and for use on horseback, they are rather unwieldy for use on foot. The larger sword has an "S" struck within the "O" and a cross potent on the reverse. The second sword was a river find and has one letter on each side of the blade, this weapon may be slightly older? I'm interested in any info' or theories and especially photos of other similarly marked blades. The final picture shows the swords together with a viking sword and two later medieval two handed swords to give an idea of scale. They are above average size for a single handed weapon. THANKS !!

THANKS !!