Just in case the link didn't answer your question..
I agree, that the number is exceptionally high. This item is unlikely to break under normal conditions. Attacking a stone or iron golem, for example, there are additional modifiers.
Slashing Weapons- Each and every breakage check (whenever you roll 'doubles' for breakage numbers, special crit/fumble, etc) is modified by -35 for attacking hard solid surfaces. Stone walls are listed in the text, so I put most hard golems, statues and such in the same category.
In addition, every strike (!) against really hard surfaces, generates a %chance that permanent damage has been done to the weapon, equal to the damage done (hits delivered to opponent).
If permanent damage is done to the weapon, it's at -5 until it can be reworked in a smithy. In my game, magic swords might need a magic smithy, but that's up to you. If a weapon ever drops below -25, it's useless as a weapon. Though you could say it attacks on a less efficient/smaller weapon crit table. Again, that's up to you.
So yes, the number is high, for normal wear and tear. But if you go hacking away at really hard items, creatures or start quarrying stone with your blade, even a magic weapon won't last long.
I hope that helps a bit.
