Why not take it further? What about Squall's gunblade when his veteran outfit arrives? Or Zidane's daggers for NIN to use?

Weapons missing from glamour purposed armor is something that always bothered me. The most likely reason is that they wouldn't want to develop a weapon for only 1 job (i.e. Yuna's staff for WHMs, Brotherhood for PLDs) and would feel pressured to develop weapons for all jobs like they did for the XIII collaboration, which would take a LOT mor time and resources than 1 or 2 outfits.