Thanks everyone for the replies. Two things definitely corrected: (i) haste won't augment a full-round action; (ii) a shocking grasp wand that does 5d6 would be much more expensive than I thought. One more thing I think the posters are saying is that wands containing spells that require attack rolls don't do critical damage even on a 20, though cast spells can crit on a 20. Is that right?
Things got a little muddied though discussing the use of weaponwand I was describing. Restating:
1) standard action, cast weaponwand and insert shocking grasp wand
2) next round, declare spell combat / spellstrike:
2a) swift action: add keen for one arcane point
2b) cast shocking grasp (not using wand) and deliver via melee weapon -- so weapon damage is added, and the spell can deal critical damage in the expanded threat range.
2c) take the (two) melee attacks granted by spell combat, electing in each attack to apply damage from wand or from scimitar, but not both, since the spell states: "You can attack normally with the weapon or use the weapon as if it were the encased wand". If choosing to treat the weapon as the encased wand, you can use the extended threat range to confirm hits, but cannot use critical damage multipliers.
Sorry I wasn't so succinct before. Please let me know if there is still something amiss with this sequence of actions.
If the above makes sense then I have a followup question: If the spellstrike misses, and I proceed to the melee attacks of spell combat AND elect to activate the wand encased in the melee weapon, presumably the charged spell in my free hand would just channel down the melee weapon on the next successful melee attack, right? So whenever I next succeed on an attack roll, I would deliver the charge from the spell, and the charge from the activated wand, correct? Thanks