Shield block + Quick shield block and cut from the air

[Elric200]

Can you use shield block quick shield block combined with cut from the air to gain a ++4 to your ac or use with shield warden to give an adjacent Allie a+4 to their AC

[Baarogue]

1. Shield Block does not affect your AC. It is for reducing damage after you have been hit. Quick Shield Block gives you an extra reaction each turn which can only be used for Shield Block

2. Cut from the Air does not require your shield. It requires a melee weapon or free hand. It is greater than most shields' AC bonus, and cannot be combined with a shield's AC bonus because they are both circumstance bonuses. It cannot be used to protect an ally unless another feat I'm unaware of allows it

3. Shield Warden allows you to use your Shield Block reaction to reduce an ally's damage after they have been hit. It does not affect their AC, just as it does not affect yours

[Finoan]

Bonuses of the same type won't stack. So raising shield while behind cover will still only be a +2 bonus to AC. Similarly, an ally with their shield raised and you using something like Guardian's Deflection won't help - because the bonuses from shield, cover, and Guardian's Deflection are all circumstance bonus types.

Also, you can only react to a particular event once. So your ally with their shield raised and you with Shield Warden could both separately react to the ally being hit to reduce the damage with your shields. But you couldn't use your regular reaction to Shield Block and then also use the extra reaction from Quick Shield Block to block that same damage again. You only get to use one reaction on the same event.

[Elric200]

Finoan I was thinking of a squishey that did not have a shield.

Is a shield not considered a melee weapon you can use with shield spikes or a shield boss as a striking weapon so a shield is more of a dual blocking and striking weapon, mostly blocking and absorbing damage.
I understand the feat was designed to make impressive sword cutting arrows out of the air with a katana or nine ring sword.

I thought shield warden was designed to defend those that did not have shields, non-melee types.

Would it be legal if the fighter with shield warden was standing in front of the cleric and the witch to use shield warden to defend both the cleric and witch as long as he had the ability to use an extra action to use only to shield block with?

[Baarogue]

The shield's "weapon-ness" is oddly defined. Under Attacking With a Shield, PC p.274, "A shield can be used as a martial weapon for attacks, using the statistics listed for a shield bash on the Martial Melee Weapons table (page 278)." Shields aren't usually weapons and can't be etched with runes. But attached weapons like the shield boss or spike are weapons, can be etched with runes, and can be used for cut from the air. It still may not be used on behalf of an ally though, unless allowed by another feat I am unaware of

If by defend you mean use shield warden to use shield block to reduce their damage after they have been hit by a physical attack, just as shield block is used for yourself, then yes. If you mean raise their AC, then no, because shield block does not raise AC. With quick shield block you could reduce the damage for either or both of them or yourself, for a total of two uses of shield block per turn if you use no other reactions. But not twice for the same recipient for the same triggering damage, as Finoan said

[Finoan]

Weaponness of shields aside, the bigger problem to consider is the Limitations on Triggers - you can only use one reaction to a particular attack.

Fortunately, Shield Warden modifies the existing Shield Block action rather than creating its own reaction like Guardian's Deflection does. Otherwise you couldn't use Quick Shield Block with it (you can't use the extra reaction from Quick Shield Block for Guardian's Deflection because it isn't "Shield Block").

So yes, you can protect both the cleric and the witch next to you - though only for different attacks. No, you couldn't use Cut from the Air and Shield Warden to protect one of them twice against the same attack.