Why is Defensive Grip not a Technique in Martial Arts?

[Icelander]

Here is an arming sword style which includes Two-Handed Sword, but has the Perk as an optional trait.

Cavalier Training

12 points

The armoured knights of Cormyr and Impiltur still exalt the mounted charge as the height of martial accomplishment. With their fine maille or plate harness as well as metal shields, few forces in the world can stand against them without powerful magic and at least for the Purple Dragon Knights of Cormyr, their own War Wizards are usually more than a match for any hostile sorcerers.

The style heavily emphasises the shock charge of heavy cavalry, with lance, sword or mace, as well as the ever-present shield. Horsemanship is extremely important, with the relationship between knight and horse being the subject of many myths and legends. While mounted, the knight uses momentum to carry himself out of melee, taking care not to be caught in the middle of infantry formations.

On foot, the knight will sometimes wield a lance in a two-handed stance, particularly if he faces pikemen or monsters larger than human size. Against men-at-arms he prefers to lead with the shield, which he’ll use for bashes and rushes as well as defence. If he loses his shield, he will often place he off-hand on the hilt of his sword in a Defensive Grip.

Attacks and Committed Attacks are common, as the knight trusts his armour to withstand any glancing blow and doesn’t feel the need for the tentative probing cuts for less armoured combatants. The knight will try to overpower and tire his foe by means of powerful strikes and whole body shield slams. Physical strength and conditioning is very important.

The grappling techniques in this style are very advanced, as the knight expects that when facing his equals, he have to get them off his feet before being able to penetrate their armour. Half-swording and finding a chink in the armour of a downed foe is a popular technique, as is a Reverse Grip Committed Attack to the Groin or Neck.

Skills: Axe/Mace; Brawling; Broadsword; Judo; Knife; Lance; Riding (Horse); Shield; Spear; Two-Handed Sword; Wrestling.
Techniques: Arm Lock; Armed Grapple; Beat; Bind Weapon (Shield); Cavalry Training; Choke Hold (Spear or Two-Handed Sword); Close Combat; Combat Riding; Counterattack; Disarm (Shield); Feint; Hammer Fist; Hands-Free Riding; Retain Weapon; Reverse Grip; Staying Seated; Sweep; Targeted Attack (Axe/Mace Swing/Skull); Targeted Attack (Broadsword or Two-Handed Sword Swing/Face); Targeted Attack (Broadsword or Two-Handed Sword Swing/Neck); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Face);Targeted Attack (Broadsword or Two-Handed Sword Thrust/Groin); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Groin Chinks); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Neck); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Neck Chinks); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Vitals); Targeted Attack (Broadsword or Two-Handed Sword Thrust/Vitals Chinks); Targeted Attack (Lance Thrust/Face); Targeted Attack (Lance Thrust/Vitals); Targeted Attack (Shield Bash/Face); Targeted Attack (Shield Bash/Groin); Targeted Attack (Spear Thrust/Face); Targeted Attack (Spear Thrust/Vitals); Trip.
Cinematic Skills: Flying Leap (Horse); Kiai; Light Walk (Horse); Mental Strength; Power Blow.
Cinematic Techniques: Dual-Weapon Attack (Broadsword and Shield); Dual-Weapon Defence; Timed Defence; Whirlwind Attack (Broadsword or Two-Handed Sword).
Perks: Armour Familiarity; Focused Fury; Grip Mastery (Arming Sword or Longsword); Leading Shield; Melee Shieldfighting (Shield); Mobile Parry (Broadsword or Two-Handed Sword); Shield Wall Training; Shoves and Tackles (Lance or Shield); Skill Adaptation (Bind Weapon defaults to Shield); Special Exercises (Lifting ST +1).

Optional Traits
Attributes: Increased ST and HT.
Secondary Characteristics: Increased FP.
Advantages: Ally (Mount); Animal Empathy; Animal Friend; Combat Reflexes; Enhanced Block; Enhanced Parry; Fit or Very Fit; Lifting ST; Signature Gear (Mount); Status; Wealth.
Disadvantages: Code of Honour (Chivalry); Overconfidence; Sense of Duty (Family or Nation); Vow.
Skills: Animal Handling (Equines); Autohypnosis; Fast-Draw: Heraldry; Meditation; Parry Missile Weapons; Polearm; Savoir-Faire; Shield (Buckler); Shortsword; Staff; Two-Handed Axe/Mace; Sport versions of all weapon skills in style.
Techniques: Defensive Attack (Broadsword); Ground Fighting; Hook; Kicking; Knee Strike; Quick-Mount; Targeted Attack (Axe/Mace Swing/Arm Joint); Targeted Attack (Axe/Mace Swing/Groin); Targeted Attack (Axe/Mace Swing/Leg Joint); Targeted Attack (Knife Thrust/Face); Targeted Attack (Knife Thrust/Groin); Targeted Attack (Knife Thrust/Groin Chinks); Targeted Attack (Knife Thrust/Neck); Targeted Attack (Knife Thrust/Neck Chinks); Targeted Attack (Knife Thrust/Vitals); Targeted Attack (Knife Thrust/Vitals Chinks); Targeted Attack (Shield Bash/Jaw); Targeted Attack (Shield Bash/Nose); All applicable armed techniques of the style with one of the optional weapons.
Perks: Form Mastery (Lance); Grip Mastery (Any); Mobile Parry (Any); Off-Hand Weapon Training; Rapid Ready (Shield); Rapid Shield Drop; Shield Wrestling (Shield)*; Shoves and Tackles (Any); Sure-Footed (Uneven); Technique Mastery (Broadsword Defensive Attack); Weapon Bond.