Again, some help with magic item pricing needed

[Jon_Dahl]

The Great Helm of the Commandant

This helmet covers the head completely and bestows the following benefits to its wearer if the wearer has the heavy armor proficiency:

• +1 bonus to the Leadership score
• Negates one critical hit of the wearer's choice per day. The choice must be made before hit points are deducted.

In addition, the wearer receives -2 Armor Check Penalty, and -5 penalty to Spot, and -2 penalty to Listen.

The helmet has arcane spell failure chance of 50%.

Faint abjuration and enchantment; CL 6th; Craft Wondrous Item, creator must have 5 ranks in the Knowledge (royalty&nobility) skill; Price ? gp; Weight 5 lb.

[Jon_Dahl]

Is the OP unclear or am I missing some vital information?