What would 'The Humble Companions of the Silver Cross and Guardians of
the Secret Peace' be in Medieval Latin?

I believe it may be something such as follows:

El Humilde Acompaņantes de la Plata Cruz y Guardianes de el Secreto Paz

The comment above appears to be an attempt at a translation in
Spanish, not in medieval Latin.

Thanks! I hope that my referring to this as 'Medieval Latin' hasn't
put anyone off. My understanding is that Classical and Medieval Latin
where pretty much identical except for some difference of spelling and
pronunciation. What I'm looking for though is the use of a medieval
lexicon, as obviously this is the name of a Christian knightly order.
Please help!

argentea crucis et secreta pacis humiles custodes

Thank you witsandknowledge!