The current implementation of (enchanted) defensive items is that you can pick block or armor at the time of the item's use.
Example:
3 vampires pile on our wizard.
The first vampire attacks and gets a great attack result.
The wizard, whose athletics is good, rolls his defense and only gets a +0 on the dice, not good enough.
He then decides to use his power 6 enchanted item to make a block.
So the attack is blocked by the enchanted item.
Minor rules interpretation:
You can wait until after you roll your regular defense to decide if you want to use your defensive item. This allows it to protect you from bad rolls, or provide 'just in time' armor to help mitigate an attack.
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The second vampire attacks.
Note that our wizard is still under the effect of a +6 block.
The vampire gets lucky and gets a +6 result. on the dice.
The wizard, hoping for a lucky roll, rolls his athletics, looking for a +4 (which would give him a defense total of +7). He doesn't get it. Even if he had managed to dodge, the block would still be broken.
The wizard can't use the same enchanted item to also generate armor, as it was already protecting him with a block effect.
The vampire hits him for some stress.
Minor rules interpretations:
1
You can't use the same item to stack both block and armor effects on yourself.
1a
You can use multiple items to stack a block and armor effect on yourself.
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The third vampire moves in for the attack
It rolls a great result too.
Our wizard rolls athletics and gets a great result. No wanting to take another hit, he uses his item (again) to provide (another) block.
Minor rules interpretations:
1
You can use your defensive item again and again (barring running out of charges or stress to power it), as long as it doesn't stack effects.
1a
The duration of armor or blocks generated by enchanted items lasts until your next action, this may mean that the block generated by your item will last into the 'beginning' of the next exchange.
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So, what items do I recommend:
2 defensive items for yourself, so you can stack block and armor effects on yourself, to defend against particularly big attacks.
3 offensive items:
1 single target weapon 10 item
1 zone target weapon 8 item
1 'non-lethal' weapon item, to allow you to take our mortals. something like weapon 4, 13 uses; depending on what weapon power you GM will allow you to justify as 'non-lethal'
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A lot of the rest of your stuff can be just left as potions, as even your potions will still be strength 10 with many uses.
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But other stuff to consider:
Defensive items that can be used by others. If you have to protect someone else, having tank armor that you can hang around their neck would come in handy.
Spell breaking prod-stick (counterspell effect). This is your goto solution for people hiding behind things like magical blocks or zone borders. You poke it with the prod stick, then your friends lay into them.
'air cannon' like potion. This lets you stuff steel ball bearings, or salt, or whatever into it and then fire it out at a damaging velocity. There for all your catch beating needs.