A couple of notes -
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The Bjornaer mystery of Sensory Magic specifically mentions you can't use its Target types in enchanted items, so they aren't of use here.
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There's no Penetration for any of the effects, so any MR will be an issue.
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There's no targeting discrimination for the panic effect, so your own side could be affected.
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[url]https://forum.atlas-games.com/t/constantly-active-enchanted-item/9885/1] was a recent similar thread, so it might be of some use.
Given how awkward creating a banner seems to be, I'm a little surprised there aren't special Range, Duration and/or Target categories someplace in the books (perhaps as part of a Mystery or House virtue) to facilitate them. House Tremere is mentioned to use enchanted pennants and dragon banners in HoH:TL. Banners made into lesser devices with an effect expiry built in sounds like something a Verditius confraternity of weavers might create for roundabout sale to nobles through their venditores. The Oriflamme is mentioned in The Lion and the Lily (pg. 88), but no concrete stats are given.