That great coat is certainly a very useful body, but if one goes for adding a cloak then the other bodies might be rather handy too. Or if one wants plenty of bodies with different types of coats, then how about getting hold of the Empire archer boxed set and using several of those bodies?
And if one is making several witch hunters, then head variants might be good - perhaps something from the Middenheim or flagellant sprues for a witch hunter with a fire-and-brimstone look for their beard and hair?
Speaking of flagellant box, that also comes with torches, as well as bits to build a captured heretic/witch. This could provide inspiration for some unit fillers, say one witch-hunter henchman building a bonfire out of logs, heretic in chains standing close by, with a second henchman keeping an eye on their captive and holding the torch.
If the Mordheim accessory sprue is still available, that might have some useful bits too, like a holstered pistol, crossbow pistol (treat as usual pistol), and a book (which should of course be titled "Malleus Maleficarum" if you can paint that fine letters on the cover).