You are holding something in you hand and you cast a touch spell and hold it. Nothing happens. But what happens if you move the item into your other hand for whatever reason? Does the spell discharge or does it count as still having been a held item?
Cast a Spell on Touch Spells in Combat says
If you don't discharge the spell in the round when you cast the spell, you can hold the charge indefinitely. You can continue to make touch attacks round after round. If you touch anything or anyone while holding a charge, even unintentionally, the spell discharges.
Emphasis mine. However, the FAQ includes this exchange:
Does wearing a gauntlet, cestus, or similar glove-like weapon count as "touching anything" for the purpose of accidentally discharging a held touch spell?
It's probably a fair house rule to extrapolate this FAQ entry to include any object the caster's holding when the spell's cast so long as the caster A) keeps at least one hand free and B) doesn't drop then retrieve the item. So, for example, casting a touch spell while wielding a longsword then transferring that longsword from one hand to another shouldn't discharge the spell, but casting a touch spell, dropping a backpack, and then retrieving the backpack would discharge the spell, as would taking one hand off a longspear, casting a touch spell, then putting both hands on the longspear. (If you're interested, there's also a whole thread here about accidental discharges during grappling. Totally safe for work. I swear.)
Hey, is this really a magus question?
Because if it is, there are actual rules for that which are both more and less generous than house rules above. This short FAQ presents this official rule covering the magus's spellstrike:
Can a magus use spellstrike... to cast a touch spell, move, and make a melee attack with a weapon to deliver the touch spell, all in the same round?
Yes. Other than deploying the spell with a melee weapon attack instead of a melee touch attack, the magus spellstrike ability doesn’t change the normal rules for using touch spells in combat.... So, just like casting a touch spell, a magus could use spellstrike to cast a touch spell, take a move toward an enemy, then (as a free action) make a melee attack with his weapon to deliver the spell.
On a related topic, the magus touching his held weapon doesn’t count as “touching anything or anyone” when determining if he discharges the spell. A magus could even use the spellstrike ability, miss with his melee attack to deliver the spell, be disarmed by an opponent (or drop the weapon voluntarily, for whatever reason), and still be holding the charge in his hand, just like a normal spellcaster. Furthermore, the weaponless magus could pick up a weapon (even that same weapon) with that hand without automatically discharging the spell, and then attempt to use the weapon to deliver the spell. However, if the magus touches anything other than a weapon with that hand (such as retrieving a potion), that discharges the spell as normal.
Basically, the spellstrike gives the magus more options when it comes to delivering touch spells; it’s not supposed to make it more difficult for the magus to use touch spells.
That On a related topic paragraph might be information you're really after, especially the implications of the section about a weaponless magus. Discussion of this ruling gets going in this thread and in this thread.