weapons and notoriety

[MrInsanity]

Sorry if this has been covered but i have looked on threads and cannot see it.
Are weapon levels in conjunction with notoriety, the reason i ask is i was in a crew on Monday, another player had less notoriety then me but all weopons were higher in level, my stats are:
Notoriety 19
Cutlass 9
Pistol 9
Doll 3
Dagger 6
Cannon 5
Sailing 11
Also are weapons opened on the main story line, side quests you have to search for or do they open when certain Notoriety are reached, i know i have opened a couple of weopons but did not take much notice of how they were unlocked.
Thanks