Umm, it really doesn't seem a good idea to grave-rob the dead and hand off the TSAB-casualty's device when we promised to give such effects back to the TSAB for the families?
Actually not a problem. The TSAB said that for most devices if they bond to a new user, they're going to stay with the new user.
Which suggests strongly that it's a non-issue because the majority of devices are unlikely to match up with a compatible new user, and will suffer major performance impediments. See for instance Yuuno being barely able to operate Raising Heart at all, while with Nanoha it immediately started up the new user registration process.
And also they're referring mainly to mementos and personal effects I think.
Checked it. Even now I'm still confused about it. Nanoha A's episode 10 (at around 5:15) one of the twin familiars (don't know which one since both were still using disguises and they are hard to tell apart anyway. Probably Lotte since Aria would be more likely to cast spells like the other masked twin was doing shortly before) has Durandal in her hands in standby form with no admiral Graham in sight. It's shortly before Chrono ambushes them. Why would she have the device ready on her if she wouldn't be able to use it? But that part has so many plot holes it looks like a training ground after Nanoha let lose with a barrage of attacks. The instantaneous teleportation to the Admiral's location at TSAB HQ in the middle of a tense situation/battle is just one of them.
We don't see many familiars/guardian beast in the series so it's hard to say one way or the other. The close range ones do not use any type of weapon (I don't think Zafira's gauntlets count as a weapon but more as armour) and you have Sam using melee weapons which I can't remember any familiar using. They either used spells (which Sam doesn't really use) or fought in hand to hand.
Since there is nothing on the wiki one way or the other I'm leaving it up to QM interpretation. But since in the Guardian Beast description on the first page of this quest it's written that they have Linker Cores but that they are filled from our own supply then I don't see a problem with a Guardian beast using an Armed Device or some Device-like Equipment when they are specialised in using melee weapons.
Remember that Devices also cost their own mana to power.
As such, most Familiars/Guardian Beasts aren't going to be using devices because the stacked mana costs will cripple most mages and the gains are relatively marginal(because Guardian Beasts are already optimized for a specific set of spells as part of their nature, Devices won't make them much better).
The only times we see familiars using Devices are:
-Admiral Graham passing his catgirls his own Device. Net effect is that it lets them cast spells they normally can't, it costs no additional upkeep(since Graham isn't using his Device at the time), and Graham is from Earth with a giant Linker Core to begin with.
-Hayate's Wolkenritter...and in this case she literally has more power than she can use, so she powers four AAA-S familiars AND their three Intelligent/Armed devices, and still has trouble regulating the remaining output.
Note that there is precedent for a Unison Device using a Device. Reinforce Eins(Unison) is a package set with the original Book of Darkness(Storage/Intelligent), and the Sword Cross(Armed), while Reinforce Zwei has her own tiny Book of the Azure Sky as a Storage device she uses for independent operations.
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