David?
er...David the Satori, not David the Hahn (thankew btw),
Read this site, might provide some insight for you:
http://swordforum.com/sfu/primer/wellmade.html
Pulled from it:
Center of Percussion - Also known as the "Sweet Spot" of a blade, the CoP is (1) the point on the blade exhibiting the lowest tendency to vibrate, and therefore is (2) the most effective portion of the blade to strike the target with. As shown in the illustration above, the fuller ends somewhere before the CoP begins. This reserves material to structurally reinforce the CoP and to reduce "wobbliness".
Vibration & Shock Dissipation Control / Harmonic Balance - While the term "Harmonic Balance" is not necessarily a historical concept or an industry-standard term, the principle behind it is worth mentioning. As with any sword, when struck, it will vibrate. Some swords may handle well but do not have sufficient shock dissipation control. In other words when a sword impacts the target, the shock transfer to the grip can be so great that it can be painful holding it. A badly-vibrating sword can be difficult to control in a fight.
A sword can have two or more "nodes" of minimal vibration - the Center of Percussion happens to be one such node but located on the blade. It is possible - given modern understanding of vibration and harmonics - to artificially position one of these nodes of minimal vibration in the grip. A poorly designed sword - no matter how beautiful in appearance - can suffer vibrational problems and thus adversely impact handling.
Tang Width / Hilt Problems
A frequently overlooked area of hidden weaknesses in swords is the hilt. After all, the hilt is the means by which the blade is manipulated and maneuvered in combat, but it also protects the hand.
The tang is the portion of the blade that enters the hilt. It is generally forged as part of the blade - only narrower so that the steel can enter into the cross guard, through the hilt, and out the pommel, where excess material is heated softer so that it can be hammered / peened. (In some cases, historically, the pommel might be forged and heated so that it expands. It is placed over the tang and allowed to air-cool, thereby contracting and securing a tight hold on the tang. The wood comprising the grip is carved in relief and added as a final step.)
A tang will ideally be one third to one half (or more if feasible) the width of the blade, though historically they were approximatley one third the width at the blade shoulder (where the tang joins with the blade). The cross guard will ideally be tightly fitted to help support the blade shoulder from lateral stresses - a poorly designed sword can place so much stress on the tang that it may compromise the sword and cause this area to bend or break.
In some cases which cannot be seen unless the sword is taken apart, the tang is a "rat tail" which is a thin, round bar of steel with a threaded end is welded to the blade shoulder. The threaded end allows the pommel (or a pommel nut) to be screwed on to fasten the hilt to the blade. While welds can be very strong and though this may be acceptable for certain knives, bear in mind that a sword is by nature a different instrument than a knife and cannot be made like a larger knife; the weight and force dynamics at work in movement as well as the stresses of use require (1) a tang that is wide enough to endure and absorb impact shock, and (2) will not bend nor break off.
Lateral stresses can cause rat tails to break off due to a concentration of force on so small an area. Some sword hilts have literally broken off swords - they look superb but they don't function quite as well. (Prior to purchasing a sword, be sure to obtain a photograph of the sword blade prior to assembly.)
Another problem with poorly made swords is loose hilts. In some cases, the grip of the hilt is bourne through with a lathe such that the hole is circular. Yet the tang is rectangular or square. In some cases the grip can move around the tang if the sword is rotated briskly left and right.
Some hilts are poorly wrapped. Some manufacturers do not use wood but instead use leather or parachute cord or cotton rope and give the handle a spiral wrap which (1) does not provide for an ergonomic grip, and (2) can come loose. In some cases, the handle wrap is resin-impregnated or epoxied but this may end up being uncomfortable when hands become sweatty. Some swords feature a twisted wire wrap over leather or ray skin. These handles can have "channels" for the wire so that the wire does not come into much contact with the hand. With poorly-made swords, however, there are no such depressions for the wire and thus can cause one's hold on the grip to be most uncomfortable. Handle wraps comprising all wire where the wire is thin can become very uncomfortable to the hands as well.
That is not to suggest that the rat-tail tang is weak, just that you may have created a handle which forces you to hold the khuk differently; i.e., that instead of "snapping" the blade down at the last nano-second, while holding it with your thumb and forefinger, you are forced to grip the entire handle and thus are feeling the vibration that always existed, but which now is transmitted to your hand/arm.
Dunno.
I repeat:
wacherass
Seriously, pal, any craftsman has tossed some failures in the the trash barrel. Goes without saying. Rescue what's salvageable, and try it again. Every project gets a little better than the previous one - that's what counts.
