*[Fleurons][1]* means here the ornament in form of flower located on a crown, like a laurel wreath.

***De foi trempée*** is a poetical inversion. Standard French would be *trempée dans la foi*, i.e. steeped in faith. 

*...épopée **des plus brillants exploits*** is more a superlative than a comparative. The deeds are not compared to anything particular. That just means something like "...an epic made of the brightest achievements".

You might also have trouble with ***ceint*** which is a very rare verb in modern French ([ceindre][2]), meaning encircled. Derived words like *ceinture* (belt) are common though.

Finally, the word ***valeur*** has a meaning mostly forgotten in modern French: *ta bravoure, ton courage*, i.e. your bravery/valor (not value.)


  [1]: http://www.cnrtl.fr/definition/fleurons/1
  [2]: http://www.cnrtl.fr/definition/ceindre