Half-Elf Arcane Training... why?

[Neo2151]

Reading up Viking Irishman's Witch Guide and half-elf says swapping out for Arcane Training "is almost a must."

But why?

Obviously I'd want Witch to be my chosen Favored Class. Arcane Training lets you "use spell trigger and spell completion items for their favored class as if one level higher," but when does that actually help? Doesn't having just a single level in the class cover all the "trigger and/or completion" requirements you might need?
When would I ever benefit from being treated as a level higher? Using a Staff is the only thing I can even think of, and that's a really minor benefit for the most part.

[Chess Pwn]

scrolls of higher level spells are spell completion items.

[LazarX]

It's hardly a "must".

[LuniasM]

I've seen people take the favored class in one of the arcane casting classes they weren't taking so they could use wands, scrolls, etc without making a check. I wouldn't say it's useful for a witch really.

[Grey_Mage]

I read this as activating the items with a higher level of potency, so a CL1 wand of vanish would last 2 rounds in the hands of this person assuming the spell was on the spell list of his favored class.

[Grandlounge]

I don't really know why a witch would pick this up. I will say it is one of my favorite traits though. It has amazing flavor a half-elf fighter who failed out of the wizard academy. He has some of the magic basics. It's a decent choice for non-casters.

You can get wands or scrolls of:
shield
heighten awareness
protection from evil
mount
mudball
Comprehend Languages
Endure elements
Identify
truestrike
floating disk
Blend
Silent image
gravity bow
etc

The wizards spell list seems to be the best to me but there are other options I'm sure

[Petty Alchemy]

Basically it does something, while Multitalented does nothing if you stay single class (especially likely as a full caster).

[graystone]

It might be useful if you pick an arcane class other than witch.

[Dragonchess Player]

It's useful for:

A non-caster to use wands without needing a Use Magic Device check.

A divine caster that wants access to some of the arcane spells.

An arcane caster that wants to access to certain spells not on their spell list (for instance, a staff magus with Arcane Training in the sorcerer/wizard spell list and the Wand Wielder arcana can use a staff with any sorcerer/wizard spell to Spellstrike, even if the spell hasn't been selected with Spell Blending).

As far as spell list choices go: bard is probably the best choice for a rogue or other character that will deal with locks and traps (wands of sift are a "steal" at 375 gp) and acting as a secondary healer with wands of cure light wounds; sorcerer/wizard is best for self-buffing, minor damage (magic missile, ranged touch spells), and utility; witch is best for debuffing (look for spells that either don't allow a save or still have an effect if the save is made) and healing.

Depending on the favored class bonus, it may not be worthwhile. Personally, I'd prefer the additional evolution points as a summoner or the extra spell per level as an oracle or witch. On the other hand, if you are planning the character to mainly take levels in one or more prestige classes (such as arcane archer/eldritch knight, battle herald, dragon disciple, or rage prophet), then the gain from Arcane Training is well worth the loss of the limited amount of times the favored class bonus will apply.