Sometimes weapons and/or armor that are randomly rolled as loot are just way too cool to toss aside. A long time ago I was running a game that got into the high levels (16+) and they did a side-quest to retrieve an optional mcguffin. One of the items I randomly rolled for loot on that adventure was a +4 Composite Longbow, Holy, Unholy, Bane x2. I didn't roll for the bane types, I picked good outsiders and evil outsiders, and named the bow The Destroyer of Heaven and Hell. The party's neutral aligned Fighter (role) kept that as his ranged weapon, for whenever he needed to use one.


Selling a +5 weapon (or any loot, for that matter) for 50% of value to replace it with more useful items is the default, but least optimal, way of going about that. Someone should have Mercantile Background and get the party 75% of value. Someone could have Ancestral Relic or similar, buy the item from the party at 50% (and get a portion of that back when loot is split), and add 100% of the item's value to their relic's value. The party's face character can make a Cha-based check to haggle a better deal than 50% of value, or even make an exchange for another item(s) of similar value. Or its full value can be used as payment for a Planar Binding or similar. Or any number of other uses that gets more value out of the loot than the default 50%.


There's no good reason, apart from house rules, to not use GMW over paying for a permanently higher enhancement bonus. An area dispel magic doesn't hit attended items, a targeted dispel magic on a creature doesn't hit that creature's items. So an enemy caster spends a (greater) dispel magic to target that one item to deprive you of up to a +4 bonus to attack and damage, so they spend a significant spell and action for an inconsequential benefit. In short, it's not even worth dispelling because the bonus is always going to be small relative to your current level. They could do some kind of chain spell (greater) dispel magic to hit all the characters and their items, but in that case you have bigger problems than the loss of a +4 to attack and damage. Disjunction is another story, but there are plenty of ways to prevent it (like Psionic Contingency: augmented Synchronicity and cast a wall spell/power to block line of sight/effect, or Contingency: Teleport behind the caster and AoO with a Sudden Stunning weapon or similar, or Celerity: cast Silence on a point in space to automatically interrupt the verbal component, or Divine Defiance and (improved) counterspell, etc.).


A magic weapon in and of itself isn't really going to contribute a lot to how much damage you deal, apart from a few very specific properties. Speed and Splitting are probably the most significant damage-increasing properties. Keen can be significant if you already have a high threat range, but that's very easy to do given how inexpensive it is (if you only get a +1 enhancement). Valorous is a huge benefit if the character does a lot of charge attacks, but it's just as cheap as Keen. Mage Bane is probably the only property that's a flat bonus to attack and damage that's worth the cost. You can try stacking Flaming, Frost, Shock, etc. but the cost scales exponentially while the benefit scales linearly, and a few more d6 of damage is barely noticeable, especially when high level enemies have resistance 10+ to several of those damage types. Subtlety gets an honorable mention because it's a flat 20k that doesn't increase the cost of other upgrades for an extra +4 to attack and damage. Apart from one big property and maybe a few small ones, it's not really worthwhile to spend anything more to upgrade your primary weapon unless you want to add other things besides damage. Non-enhancement-priced effects like Subtlety, Sudden Stunning, Displacement from OA, special materials, wand chambers, weapon crystals, etc. are generally worthwhile because they don't cause the cost to scale exponentially. Wrathful Healing is one of those other things that's generally worthwhile at the higher levels.