I'm not 100% sure I'm correct, but I believe that the fact of whether or not a nation's weapon shop will sell Silver Arrows depends on the regions the nation has under control.
In most cases that will be the number one nation, seeing as they have more regions, but I'm pretty sure what region you have under control is what matters to what is sold. Hence having a terrible weapon shop when in last, and great one when in first.
Although I'm not sure what region you would need to control for silver arrows, if that really is what it depends on... It would seem it is Valkurn Dunes (my guess), since Bastok and San d'Oria are always fighting for it, and the one who has control usually is also ranked first if Windurst isn't (giving the leading country the arrows). And Windurst almost never has control of the Dunes, so they almost never get silver arrows.
There has also been times where San d'Oria has been in first, but still didn't sell silver arrows. So that would explain it.
I could be wrong, but just something to consider :D
Edited, Mon Feb 16 03:02:17 2004 by RKenshin
____________________________
75RNG.75NIN.75WAR.75SAM.75DRK.75MNK.75DRG.
+ 12BLM, 10WHM, 2 RDM! lolmage
Merit 405~
lolLJ