Okay, under the ICE rules, if you ever missed in melee combat, there was a 50/50 chance that there would be a clash. Obviously, fighters who got hit a lot didn't have much to worry about their weapon breaking. :)
The following information is my condensed version of how it worked, and is excerpted from Character Law/Campaign Law section 7.3.6, catalog #1300, second U.S. printing by Iron Crown Enterprises.
Please note that this all may have changed when the rules were re-written to the Standard System that ICE uses now. However, since the ST/BF numbers for most items were probably done under the old system, this is probably still fairly relevant.

If the 50% roll indicated a clash, there was a 50/50 chance of the swung weapon clashing with the defenders weapon, or with the shield. Only one d100 was actually rolled: 1-50 was a whiffle, 51-75 was weapon, and 76-100 was the shield.
If a clash was indicated, the STrengths of the two clashing items were compared. The item with the higher Strength could NOT break. If the items were tied, then there was a possibility of both items breaking.
Roll d100 open-high (any roll of 95 or greater is kept and rolled again, summing all subsequent rolls; if 95+ is rolled again, keep rolling).
Compare the result to the BF (Breakage Factor) of each item that it is possible to break in this particular clash (usually only the weaker STrength, but in the case of a tied STrength, compare the d100 roll to both items' BF). If the d100 roll is greater than the BF, the item is broken.

Snap!

This usually sucks.

GemStone did NOT have breakage of armor in the past; only weapons and shields could break. However, when AT4 heavy hide was removed from the game, all special-order armors (now known as AsG's 10, 15, and 20 bought from Aznell) required the attention of a GM to fix their ST/BF numbers, so the possibility is there.

Here, then, is the chart of ST/BF numbers, direct from CL/ChL from ICE. I've included the bows, sling, bola, and other such items for completeness, despite the fact that they don't actually figure in melee combat. I did leave out the various pieces of barding (horse-armor), since we haven't got any horses. ::grin::

  For column #3, AT (Armor Type), read AsG (armor sub group).
 
 ID#   Name                                      AT     ST    BF
 ---  ----------------------------------------  ----   ----  ----
 101  Leather Jerkin                               5     5    80
 102  Arm Greaves
 103  Leg Greaves                                       55   120
 104  Leather Coat                                 6     5    80
 105  Reinforced Leather Coat                      7    15    85
 106  Reinforced Full-length Leather Coat          8    15    85
 107  Leather Breastplate                          9    18    90
 108  Chain Shirt                                 13    40    95
 109  Full Chain                                  15    40    95
 110  Chain Hauberk                               16    40   110
 111  Breastplate                                 17    55   160
 112  Half Plate                                  19    50   145
 113  Full Plate                                  20    55   160
 114  Target Shield (targe)                             40   140
 115  Normal Shield                                     45   155
 116  Full Shield                                       50   170
 117  Wall Shield                                       60   185
 118  Leather Helmet                                    10    80
 119  Superior Leather Helmet                           20    85
 120  Plate Helm                                        25    90
 121  Pot Helm                                          55   120
 122  Full Helm                                         60   145
 123  Visored Helm                                      55   135
 124  Aventail                                          40    95
 501  Bastard Sword                                     75   175
 502  Battle Axe                                        70   155
 503  Blackjack                                          5   120
 504  Blowpipe
 505  Boar Spear                                        30   135
 506  Bola                                              12    75
 507  Boomerang
 508  Broadsword                                        75   160
 509  Cat-o'-nine Tails                                 10    75
 510  Claymore (claidhmore)                             75   155
 511  Club                                              10   140
 512  Composite Bow
 513  Crossbow (heavy)
 514  Crossbow (light)
 515  Cudgel                                             8   130
 516  Cutlass                                           75   155
 517  Dagger                                            18   195
 518  Darts
 519  Dirt                                              32   175
 520  Falchion                                          75   160
 521  Flail                                             60   150
 522  Foil                                               8    95
 523  Gauntlet                                          45   110
 524  Halberd                                           25   150
 525  Handaxe                                           70   160
 526  Harpoon                                           20   135
 527  Javelin                                           17   105
 528  Jo                                                20   145
 529  Katana                                            70   155
 530  Lance                                             30   130
 531  Lasso
 532  Long Bow
 533  Longsword                                         75   160
 534  Mace                                              65   250
 535  Main Gauche                                       18   190
 536  Morning Star                                      60   145
 537  Net (fishing)                                      1    20
 538  Net (gladiator)                                   15    75
 539  No-dachi                                          75   165
 540  Nunchaku                                          20   125
 541  Pick                                              20   120
 542  Pilum                                             18    90
 543  Quarterstaff                                      20   140
 544  Rapier                                            30   100
 545  Sabre                                             70   150
 546  Sai                                               30   210
 547  Scimitar                                          60   150
 548  Short Bow
 549  Short Sword                                       75   185
 550  Shuriken
 551  Sling
 552  Spear                                             15   130
 553  Tomahawk                                          25    80
 554  Tonfa                                             20   130
 555  Trident                                           30   140
 556  Two-handed Sword                                  75   200
 557  War Hammer                                        60   155
 558  War Mattock                                       60   145
 559  Whip                                              10    75
 
 
 
 Material Type     Magic Bonus                          ST    BF
                                                       ----  ----
 mithril                + 5                            +20   +40
 eog/ora                +10                            +15   +30
 ithloss/imflass        +12                            +20   +40
 laen/mein/glaes        +15                            +24   +65
 shaalk/vultite         +20                            +15   +40
 rularon/rolaren        +20                            +20   +65
 eorake/eonake          +20                            +20   +55
 galvorn/golvern        +25                            +24   +99
 star/veil iron         +25                            +24   +75

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