This is why I said Luthien cannot be hold acountable for the "letting him in" part. And as elves have another time perspective, her delaying the reporting could have been overlooked a bit - if Beren happened to be unarmed.The Girdle clearly allowed Beren in though, and how much control does Thingol have over it? Even Melian knew the Girdle would be breached one day.
An bow is also hunting equipment, and we know Beren does not hunt. Last time the Tolkien Professor mentiond Beren having no weapons as one of the signs to Luthien that Beren is interesting and different. An unstrung bow is basically just an ornate stick and not an active combat weapon. This gives leeway for Thingol's coutiers to chose not to accusse Luthien publicly of treason.
Having no repercussion for such a serious offence like knowingly letting an armed intruder roam freely in her county would make for bad optics for the audience as
1. it would show Luthien as massively arrogant for considering herself so much above the law
2. it would show Doriath as ridden with nepotism for her to expect to get away with it
we do avoid this to a degree by making the offense less severe.
Is Luthien not shown very long-haired in this picture too? And should she not still have relatively shortened hair still? So the picture clearly is no meant literally.But it does show up in the Lays of Beleriand, meaning it made its way into some material for poetry, and I don't intend for him to be fighting Dwarves with an antler like Frey at Ragnarok. Plus why else would Beren be shown with a sword in artwork like Alan Lee's that features on the cover of books if he wasn't meant to have it throughout his exploits (the presence of Luthien and Huan seems to indicate he had it as late as Huan abandoning Celegorm)?
an atlatl could be used one-handed, if you use your fingers skillfully to hold the dart for one second when you attach the thowing stick to the dart's end - just saying... ;-) and a dart quiver can be attached to one's side and the atlatl itself can be carried behing one's belt like a knive would... ;-) all feasible to be used one handed - no crossbow necessary...I agree that a bow is not going to work for a one armed man, but why not a spear?
And a crossbow needs two hands to be loaded - or not?
If you not like the atlatl then of course: thowing arrows (Dutch arrows, Swiss arrows) - and small fledged javelins.
You carry a bundle of them in one hand, stick them point down vertically in a row in front or to the side of you into the ground and then pick up each just before you throw it (just like when using a atlatl one-handed, just without the atlatl, but just with the fingers instead).