glowglyph rune--shape of the area of effect when used for blinding

[J. S.]

http://www.d20pfsrd.com/races/core-races/dwarf/forgemaster-cleric-dwarf/

"Glowglyph: The inscribed item sheds light as a torch. As a standard action, the bearer can command the rune to erupt in a burst of light as a shield with the blinding special ability with a burst radius of 5 feet per glowglyph rune inscribed on the item. This expends all glowglyph runes on the item."

http://www.d20pfsrd.com/magic-items/magic-armor/magic-armor-and-shield-spec ial-abilities/blinding/

"A shield with this ability flashes with a brilliant light up to twice per day upon command of the wielder. Except for the wielder, anyone within 20 feet must make a successful DC 14 Reflex save or be blinded for 1d4 rounds."

Is the only allowed area of effect shape a circle? Or would a character be allowed to command the runes to erupt in a semi-circle or cone (to represent being placed on the front of his shield)?

[Claxon]

Technically a sphere centered on the wielder not a circle, but yes.

You can't aim it to avoid your friends.

[J. S.]

Darn, that makes this ability way less useful.

The idea of a shield erupting in a flash of light blinding enemies in front of you sounds like classic fantasy. Since the area of effect is a sphere, it seems like a party member would always be too close to use this ability.

Maybe applying the runes to a sling bullet or crossbow bolt would be more useful.

What is involved in "commanding the rune to erupt"? It's a standard action. Can it be done at range?

What are the rules for deciding where a projectile goes after it hits or misses?