harry potter - Did Dumbledore himself take the Sword of Gryffindor under conditions of "need and valor"?

In Chapter 33 (The Prince's Tale) of Harry Potter and the Deathly Hallows, it is revealed that the Sword of Gryffindor "must" be taken under conditions of "need and valor", and that kind of explains why it was placed in the frozen lake, rather than just having it placed outside their tent.

"Now, Severus, the sword! Do not forget that it must be taken under conditions of need and valor."

We also know, from the same chapter, that Dumbledore himself used the sword to destroy the ring Horcrux.

"Marvolo Gaunt's ring lay on the desk before Dumbledore. It was cracked; the sword of Gryffindor lay beside it."

This begs the question of whether Dumbledore himself had to receive the sword under said conditions in order to be able to use it on the ring; or is he excluded from that requirement by being the Headmaster, by knowing advanced magic or something like that?

Two points to clarify:

1. 
   
   

   I take the "must" part to implicitly mean "in order to use it" or be its "true master". Snape could obviously "carry" it, for instance , but maybe wasn't able to use it properly? (Then again, he was the Headmaster at that time, so maybe he could use it as well if we assume the above).

   
   


2. 
   

   Harry himself had already received the sword once under said conditions, so does this imply that one needs to "renew" his "worthiness" of the sword? This in turn implies that (if we don't assume Headmaster privilege) Dumbledore would need to have "renewed his worthiness" sometime between the end of book two and the beginning of book six, even if he had shown valor at an earlier episode of his life. (I realize that it was Ron and then Neville who ended up using it, both indeed exhibiting valor, but that really wasn't the intended plan).