OK, using a spiked shield is
Shield Spikes wrote:
Benefit: These spikes turn a shield into a martial piercing weapon and increase the damage dealt by a shield bash as if the shield were designed for a creature one size category larger than you (see “spiked shields” on Table: Weapons). You can't put spikes on a buckler or a tower shield. Otherwise, attacking with a spiked shield is like making a shield bash attack.
An enhancement bonus on a spiked shield does not improve the effectiveness of a shield bash made with it, but a spiked shield can be made into a magic weapon in its own right.
and using a shield to bash normally means you forfeit the sheild's ac bonus.
Improved Shield Bash (Combat) wrote:
You can protect yourself with your shield, even if you use it to attack.
Prerequisite: Shield Proficiency.
Benefit: When you perform a shield bash, you may still apply the shield's shield bonus to your AC.
Normal: Without this feat, a character that performs a shield bash loses the shield's shield bonus to AC until his next turn (see Equipment).
A Klar is just a fancy version of spiked shield; you still lose your shield benefit when attacking with a Klar
Klar wrote:
Traditionally a Shoanti blade bound to the skull of a horned spirestalker (a breed of Storval Plateau giant gecko), in recent years the armorers of southern Varisia have started crafting these bladed shields from iron.
Benefit: A klar can serve as a weapon or a type of shield.
As a Weapon: An attack with a klar is treated as an attack with shield spikes.
As Armor: The klar functions as a light wooden or light steel shield when used to defend in combat.
Weapon Feature(s): special
A Madu doesn't have the same language, in fact is says
Madu wrote:
The madu is a round, light shield with two animal horns—usually from an antelope—extending from opposite sides of the shield.
Benefit: If you are proficient with the madu, you may use it to fight defensively with a –2 penalty instead of the normal –4, and your attack penalty for using Combat Expertise improves by +1 (minimum –1 penalty). You cannot hold anything else in the hand that bears a madu. If you are not proficient with the madu, treat it as a light spiked shield.
Which suggests that using a Madu is not like using a spiked shield (assuming proficiency). Does this mean that a proficient user of a Madu, gets both to attack and use the Madu`s shield bonus, with only 1 hand occupied ?
*All quote from D20pfsrd.com
