Yes, that one's very old. The last two lines are completely nonfunctional today, as the weapon imbues no longer have to be cast on main- or offhand.
Let's completely rewrite this:
Code:
#showtooltip
/castsequence reset=5 Lightning Shield, Windfury Weapon, Flametongue Weapon
(typed on my phone, didn't test ingame)
I put Lightning Shield first, since it only has a 30min duration, so you'll have to re-apply it more often. Left the reset time at 5, as that means 5 seconds after the last use, not after the first spell in the sequence. Feel free to increase that number, though.
Hmm, I might actually use that macro on my Enh alt, didn't touch that char much since 9.0, but I did put those spells back on tertiary bars, frowning at the clutter.
PS: just to clarify, for the other specs, just put Lightning Shield on the button, the weapon imbues have no effect on spell casts.