If a familiar is nearly as smart as a human (or smarter than the average human, depending on the master's level), and many of them have a high Dexterity score, and familiars inherit all of the master's skills, can it be inferred that a familiar for whom it is physically possible to hold an object (for instance a hawk) can also use a weapon? If that's too much of a stretch, can it be given something like holy water or an acid bottle to drop or throw on the enemy?
What about a familiar that can obviously use a weapon (such as the Imp, which is stated as generally attacking with a shortsword)? What are its weapon proficiencies? Does it gain the same weapon proficiencies as its master? (Arguably not much for a Wizard, but already quite a few weapons if we're talking about a Sorcerer.)
Best Answer
Can a familiar hold an object?
Most can somehow. This will rely on the DM's generosity to some degree, but a familiar's ability to manipulate items physically should be on par with a similar real-life animal. This means, for example, having creatures carry items and drop them is well within most creatures' abilities if their Strengths allow. (Although I suggest wiping off an item before retrieving it yourself. Toad spit. Ew.)
Can a familiar wield a weapon?
A creature doesn't gain its master's weapon proficiencies when it becomes a familiar. A familiar's type is magical beast, yet neither magical beasts nor animals gain weapon proficiencies beyond their natural weapons due to their types, so the creature will suffer a −4 penalty on attack rolls with any other weapons unless it somehow gains proficiency.
That said, even the Intelligence 15 hawk familiar of a level 20 wizard probably lacks the physicality to wield a weapon designed for humans effectively, and such a wizard's toad familiar almost certainly can't, but ask the DM. (I don't doubt that, for example, intelligent hawk culture would eventually develop appropriate weapons, but that's beyond this question's scope.)
Can an improved familiar use weapons?
This is more complicated. Creature with appropriate manipulators can wield weapons, but whether a particular improved familiar can do so is up to the DM. However, an improved familiar with a type other than animal keeps its type, and, for example, outsiders are proficient with all simple and martial weapons, making an imp with a sword a thing. Just be sure the sword's sized appropriately.