I've struggled a bit with what I consider to be somewhat vague sidebars on pages 252 & 253 in regard to Blocks. Thus I've written out other examples of how I think Blocks work and am hoping to get clarification on them. An answer along the lines of: "Example 1:Correct, Example 2: Incorrect—and then providing the correction" is highly appreciated.
1. Standard Fist Fight:
Attacker Fists Skill of Average (+1) who is punching a Defender using the Athletics Skill of Average (+1) to Defend. The Attacker Rolls [+,+,-,■] for a total of +2, vs the Defender's Roll of [-,-,■,■] for a total of -1. The result is the Defender taking 1 Physical Stress.
2. Guns vs. Armor:
First Exchange: Attacker Guns Skill of Fair (+2) who is using a Pistol (Damage: 2) targeting a Defender using the Athletics Skill of Average (+1) to Defend who also is wearing a Kevlar Vest (Armor: 1). The Attacker Rolls [+,-,-,■] for a total of +1, vs the Defender's Roll of [+,-,■,■] for a total of +1. The result is the Attacker successfully connects with the Defender, the Pistols Damage takes effect modified by the Armor resulting in the Defender taking 1 Physical Stress.
Second Exchange: (Same Attacker and Defender as in First Exchange) The Attacker Rolls [-,+,■,■] for a total of +2, vs the Defender's Roll of [+,+,■,■] for a total of +3. The result is the Attacker misses the Defender completely, the Pistols Damage and Armor have no effects resulting in the Defender taking Zero Physical Stress.
3. Weapons vs. Natural Armor:
Attacker Weapons Skill of Fair (+2) who is using a Dagger (Damage: 1) targeting a Defender using the Athletics Skill of Average (+1) to Defend who also has Supernatural Toughness (Natural Armor: 2). The Attacker Rolls [+,+,■,■] for a total of +4, vs the Defender's Roll of [+,+,■,■] for a total of +3. The result is the Attacker successfully connects with the Defender granting one extra stress from the attack itself and applying the Dagger's Damage as well; however, the Natural Armor reduces the damage by 2 resulting in the Defender taking Zero Physical Stress.
4. Guns vs. Evocation Blocking Spell:
First Exchange: Attacker Guns Skill of Fair (+2) who is using a Pistol (Damage: 2) targeting a Defender using the Athletics Skill of Average (+1) to Defend who also Blocking with an Evocation Shield Spell, Shifts of Channeled Energy of 5, split between 3 shifts for Block Power and 2 Shifts extended Duration for 3 Total Exchanges. The Attacker Rolls [+,+,■,■] for a total of +4, vs the Defender's Roll of [+,+,■,■] for a total of +3. The result is the Attacker's shot hits the Block, but doesn't bypass it. The Pistol's Damage is deflected.
Second Exchange: (Same Attacker and Defender) The Attacker Rolls [+,+,+,■] for a total of +5, vs the Defender's Roll of [+,+,-,■] for a total of +2. The result is the Attacker shot hitting the Defender and the Block, with the Pistol's damage bypassing the Shield spell—thus ending the spell one exchange earlier than the base duration paid for in shifts of power—and dealing 2 Physical Stress to the Defender from the Damage of the Pistol.
Third Exchange: (Same Attacker and Defender) The Attacker Rolls [+,-,-,■] for a total of +1, vs the Defender's Roll of [■,■,■,■] for a total of +1. The result is the Attacker's shot hitting the Defender (the Block is gone), and dealing 2 Physical Stress to the Defender from the Damage of the Pistol.
5. Guns vs. Evocation Armor Spell:
Attacker Guns Skill of Fair (+2) who is using a Pistol (Damage: 2) targeting a Defender using the Athletics Skill of Average (+1) to Defend who also Blocking with an Evocation Armor Spell, Shifts of Channeled Energy of 5, split between 4 shifts for Armor of 2 and 1 Shift extended Duration for 2 Total Exchanges. The Attacker Rolls [+,+,-,■] for a total of +3, vs the Defender's Roll of [+,+,■,■] for a total of +3. The result is the Attacker's shot hits the Defender, the Pistol's Damage is modified by the Armor, resulting in dealing 1 Physical Stress to the Defender. Armor Bonus Stays in Effect for the next exchange.
6. Guns vs. Evocation Block Spell and Natural Armor:
Attacker Guns Skill of Fair (+2) who is using a Pistol (Damage: 2) targeting a Defender using the Athletics Skill of Average (+1) to Defend who also Blocking with an Evocation Block Spell, Shifts of Channeled Energy of 4, split between 3 shifts for a Block Strength of 3 and 1 Shift extended Duration for 2 Total Exchanges, who also has Inhuman Toughness (Natural Armor: 1). The Attacker Rolls [+,+,-,■] for a total of +3, vs the Defender's Roll of [+,-,■,■] for a total of +1. The result is the Attacker's shot hits the Defender, the Pistol's Damage bypasses the Shield spell—thus ending the spell one exchange earlier than the base duration paid for in shifts of power, but Defender's Natural Armor absorbs the rest of the Damage resulting in the Defender taking Zero Physical Stress.
Any other examples you have that may help explain Block Function will be helpful as well.
Extra Credit, Optional Rule Example from Page 253 Side Bar: EC. Guns vs. Evocation Shield Spell in lieu of Athletics Dodge:
Attacker Guns Skill of Fair (+2) who is using a Pistol (Damage: 2) Has the Drop on the Defender who doesn't have their Shield spell up yet. The Defender rapidly casts their Evocation Block Rote Spell in place of using Athletics to Dodge. The Blocking Spell has 5 Shifts of Channeled Energy, all of it applying to a Block of 5 with no extra duration for a spell lasting for one Exchange. The Attacker Rolls [+,+,■,■] for a total of +4, vs the Defender's Newly Established Block, the shot hitting the Defender and the Block, the gun's damage overloading the Shield by 1 causing 1 Physical Stress to the Defender.