I believe the "look at the model" is exactly what caused all this confusion and over-thinking. That terrible phrase should just be ignored, because BG is still running tournaments WYSIWYG. Conversions are good for the hobby and good for the store, despite what GW infers.
The power weapon choices themselves seem fairly balanced.
If an option says Power Weapon - X pts, one could buy his choice of a sword, axe, maul or lance. If the options says Power Sword, then power sword.
Death Cult Assassins wield two power weapons. So if you want Death Cult Assassins wielding one power sword and one power axe, that's cool too. See "More Than One Weapon" on BRB p. 54 for relevant details. Essentially, you choose one weapon for each model for the Assault (no splitting attacks) and you get +1 Attack for dual-wielding power weapons.
Sam's completely spot-on regarding rule fluidity. Anything could change at any time, and there's very little the store can do. As always, you take your chances... or you buy magnets from the store.