Macro for Sheild dancing

Hi,
I'm trying to combine shadowmourne swapping with shield and mace + Flash of light in same macro.

#showtooltip
Flash of Light
/equip Royal Scepter of Terenas II
/equip Icecrown Glacial Wall
/equip Wrathful Gladiator's Libram of Justice
/cast Flash of Light

however, every time I press it doesn't work well, usually causing me to double press to trigger flash of light.

any idea how can this work?

changing weapon while in combat causes a 1.5 gcd.
So, while in combat, first press = it equips weapon + off hand + relic -> second press = flash of light

You may put "flash of light" on first line of the macro to avoid this BUT, I guess, the first "flash of light" casted with this macro will not count the spell power of healer's weapon

any idea of a better macro?