Hit Points  Hit Points depend upon Constitution and Size (body weight):   HP = SIZ / 2  (round up)   &  HP falling below -CON = DEATH

Combat:  Roll Attacker weapon skill & damage, Defender may Parry, use Heroic Defence, subtract Armour, then take any damage from HP.

Heroic Defence  Heroic Defence (aka Dodge) is the ability which allows heroic characters to avoid death, injury and similar horrible fates. It can reduce damage through sheer heroic luck. A Defence roll may be attempted once per attack, after any parrying etc. Success reduces damage by 10 (Special by 20; Critical negates ALL damage). A character using Defence must take some sort of evasive action, such as: Shift back (5ft-step), or fall prone, or a similar action which disadvantages their subsequent movement. (See the Experience System).

Parry  Successful parry blocks an attack, absorbing damage up to the Armour Points of the parrying item. Any excess damage applies to the parrying limb but may be reduced by armour, and also reduces the parrying weapon armour points. Special parry blocks double the normal amount of damage. Critical parry blocks the blow entirely, without damage to the parrying weapon.

Armour  Armour reduces incoming weapon damage by it's Armour Points (AP) value (except from Criticals, which bypass armour). 
Armour does not affect damage from other sources (e.g. falls, Fireballs). Composite armour normally provides its average AP value.

Hit Location is not usually rolled but if it is required: roll d20 for Location and d6 for Sub-Location (see Grievous Injuries).

Critical Hits  Critical hits automatically inflict the maximum damage that could be rolled for the weapon, and by-pass any armour.

Special Hits  Special hits have special effects, which vary according to the type of weapon:
SLASH:  If a wound is inflicted, it will bleed (target lose 1hp/rnd unless staunched); otherwise, a minimal 1hp is inflicted (no bleeding).
CRUSH:  Target make CON v Damage, or hit location stunned d3 rnds; and Parry weapon or armour takes 1 damage (see Crushing Blow).
IMPALE: Double normal rolled damage, weapon sticks in, difficult to remove, prevents healing and can cause damage (see Impalement).
ENTANGLE: Target is immobilized at least partially, as if grappled: roll for hit location affected (chest includes arms; abdomen inc. legs).
KNOCKBACK: Target make SIZ v Damage, or be knocked back 1ft per point (taking d6 per 10ft if an object is struck) and DEXx5 or fall.

"Golf-Ball" Effect  Powerful hits of base 10+ damage inflict Knockback (above) and damage weapon/armour as Crushing Blow (below).

Crushing Blow  Special Crush hits automatically do 1HP damage to parrying weapon/shield or Armour location struck loses 1AP.

Impalement  The wielder can pull out the stuck weapon immediately with a difficult skill roll, or full-skill on later rounds (but this makes attacks on them easy). If the weapon is larger than a knife or arrowhead, the victim cannot be healed until it is removed and if they move significantly will take half the initial damage again. To remove it is a full-round action requiring a STR v initial damage roll - failure causes d3 further damage. (Out of combat, these attempts are easy). Breaking off the weapon requires a roll of STR v Weapon HPs (arrow = 2).

Brawling: Unarmed combat punches, kicks, head-butts, etc. Can parry Brawl/Grapple attacks; parrying Grapple holds is Easy (x2). Can parry other attacks, but successful parry takes minimum damage on the parrying limb. Hits on armed/armoured targets take damage equal to that blocked (but this damage is reduced by armour, as Gauntlets).
Knockout Attacks require a Difficult attack roll (unless Brawling) to target the head. Damage >= HP knocks target out for d10+10 rounds.

Grappling: Can parry Grapple/Brawl attacks. If parried by weapon/shield, the weapon/shield arm is grabbed. Success grabs a random location and allows a grapple effect next round, if hold maintained (Special/Critical automatically maintain 1rnd & give +3/double rolls): 
Immobilize (STR v STR cannot act or use held limb),   Throw (STR+DEX v SIZ+DEX thrown d6x3ft, fall prone, DEXx5 or d6 damage), 
Disarm (immobilized limb: STR+SIZ v STR drops held weapon/item),   Knockdown (STR+SIZ v STR overbear, DEXx5 or 1 damage), 
Injure (inflict d3+db damage, STR v STR to keep hold),   Strangle (CONx1 or d3 damage, STR v STR to keep hold and auto-maintain), 
Change (DEX v DEX swap hold to chosen locn),   Extend (DEX v DEX+SIZ grab another chosen locn, if failed STR v STR to keep hold). 
Once held, target can attack grappler only with Short-range weapons (dagger, fist, etc). 
Overbearing Attacks require a leaping Grapple/Shield charge attack roll. Success gives an immediate chance for a Knockdown Grapple effect: STR+SIZ v STR. (This tactic is often used by wild animals, which usually have Grapple skill equal to their Claw attack skill).

Weapons Expertise  Professional combat specialists can have Expertise in particular weapons (aka Martial Arts in BRP). Attack rolls which are also under their Expertise (with that weapon) gain an extra attack and inflict double normal rolled damage with natural/kata weapons. 

Expertise/Martial Arts  Expertise in weapons can give special combat abilities (see Martial Skills: Expertise and Abilities). Certain sects of warrior-monks have taken  this to the extreme and have turned it into an art. Such monks are normally trained with 'Open Hand' (a.k.a. Fist/Brawl), Grapple and two weapons 'Kata' (i.e. patterns of attack). The training allows them to gain Expertise in these attack forms and therefore up to four special combat abilities (normally Flying Fists, Flying Feet, Deadly Hands and Butterfly Effect), which can make them formidable in combat even when unarmed. Weapons for which Kata attack-patterns can be learned include: staff, club, dagger, polearm, spear, kama, nunchaku, siangham, shuriken. 

"Off-Hand" Weapons  There are no 'left-hand' skills. Off-hand weapon use is at HALF normal skill (unless ambidextrous/either-handed).