GURPS, for all its efforts to have rules for everything ever, leaves a number of things unmentioned and without rules. Some of them are minor and only likely to impact anything if you really are trying to dig in depth, others are a bit more jarring if you try to use them.
First up, mass production at higher tech levels of blades and similar. Low Tech has the Cutlass at $400, and mentions that the one listed in basic set for $300 is a mass produced version. This gives us a functioning mass production modifier of .75x. Thing is, that's at TL4, age of sail, when even mass produced they still had to be built Ye Olde Fashioned Way. What happens at high tech, when a properly set production line can churn out good or fine quality blades by the hundreds or thousands? Corners can be cut (or not, if it's cheaper) in ways never before possible to allow for ease of production, at the cost of appearance, even if the blade quality itself is unaffected. Many modern blades use the standard rules for the free upgrade to fine quality, or 60% price break to purchase good. These mass production musings are for such things as blades made of quality modern steel, with hardly any effort put into actually sharpening the edge and such things as ugly molded plastic grips. An example would be some things such as the Cold Steel machetes, made of pretty good steel and weighted exactly as they should be (most fall under the classification of Falchions or Small Falchions for rules), but with every corner available to cut without ruining the blade. They also come with a nearly blunt machete/utility edge, even if they're made of the same steel as the finer blades; for example, both the 1917 Bowie knife and the Bowie Machete are made of 1055 Carbon steel. As most blades are machine tempered these days as an automated process, it's unlikely that other than the anti-rust coating on the machete (which is meant to be abused) and generally simpler geometry the blades differ any. The true bowie has an MSRP of $200, online retail of $117. The bowie machete has an MSRP of $30, and an online retail of $25. Alternatively, cheap quality (20% price of usual) would explain the difference perfectly, with the difference being in the quality of the edge as purchased, provided that it is permitted to raise the quality by sharpening and refinement (assuming that mass production, rather than necessarily using poor quality steel that cannot be improved, merely doesn't bother with a fine or even good edge, and other such niceties that can be remedied with sufficient time and skill in the required areas such as blade sharpening, woodworking, even if the skill or equipment to craft a good or fine blade from scratch is not possessed). Otherwise, I may house-rule that a modern mass produced blade is treated as an opposite version of a display weapon, valued at the next step down (A good quality blade becomes cheap price, and receives reaction penalties from those who know or appreciate weapons equal what a display weapon would gain in reaction bonuses)
Other questions with GURPS are the treatment of improvised weapons; many things receive fairly sizeable penalties to use as weapons without the Improvised Weapon Master perk; Among these is the Sledgehammer, treated as a maul at -2 to skill, despite all historical examples of war maul I can find being essentially just sledgehammers. So far the main difference I've been able to come up with was possibly the use of a metal haft, or at least metal clad, but this doesn't explain the penalty to skill when they are identical save for weight and price (Sledgehammer is listed at 15 lbs, maul at 12. Of course, sledgehammers are commonly available in different weights, would a smaller sledgehammer simply be a maul at 1/8th price? The splitting maul, essentially a lightweight but sharpened sledgehammer, gets a -3 to skill to use with two handed axe/mace skill. As someone who's spent much of his life swinging axes, sledgehammers, and so on, this seems somewhat questionable. Still, not particularly hard to ignore those penalties and just treat it as using base skill.