Here is a rules option I just banged out in response to a thread on chain weapons over on the SJG Forums. I didn't want to lose it, so I'm reposting it here in a cleaned-up and edited form.
People make dedicated weapons for a reason. Part of this is because the form and quality needed to have a man-killing weapon that won't fail against other weapons and armor doesn't match that of a similar tool. The axe developed from a tool, but the features you look for and need (and don't need) in a work axe are not the same as a weapon. Swords, even more so - compare a rapier and a machete and you'll see what I mean more clearly. Even simple weapons like clubs have weaponized versions along side improvised versions.
But the Rule of Cool insists that dedicated weapons are not as effective as improvised weapons. A stool or frying pan is a better club than a club made for war. A handful of sand in the face is worse than a spray of mace. A fireman's axe is better than an axe made with the express purpose of killing people, because grabbing a fire axe off the wall to fight with is bad ass. By the Rule of Cool, the tow chain/chainsaw chain/whatever will be a better weapon than a kusari, just like a broken off glass beats a knife.
Thus, I present the following Rules Option:
Rule of Cool (Improvised Weapons)
When you first use an improvised weapon in combat, it is an inherently superior and more effective weapon than actual dedicated weaponry. The weapon is only -1 to hit (no penalty, with the Improvised Weapons perk), does +1 damage compared to the weapon it most resembles, and the penalties listed under Cross Cultural Encounters (Martial Arts, p. 212) apply to all of your opponents even if the defender is familiar with the basic weapon you are aping.
This normally lasts only one combat, extended scene in an adventure (breaking into a complex, escaping the prison, that first day in gladiator school), or action sequence.*
Another variation of this rule says the improvised weapon is always better. Pick one aspect of the above - improved skill, improved damage, or penalties to the defender, and apply them whenever the weapon is used. This never changes, although a different improvised weapon of the same type might give you different bonuses (a heavier umbrella might be +1 damage while a lighter one only removes the skill penalty.) Such weapons never count as cheap quality.
* This is the Jackie Chan rule. Pick up a ladder, fight with it, abandon it.
** This is the John Steed/Tika Waylan/that guy with the stool from the Brust books rule.