“I was compared to Sweeney Todd once,” Brooklyn barber David Arce told me with a straight razor pressed to my throat — as an involuntary arm twitch brought on by his Tourette’s syndrome punctuated the macabre joke.

And so began the most hair-raising shave of my life — and also one of the best.

Arce, 28, has Tourette’s, which causes a tic where his arms spasm several times a minute. Was I worried that the guy with a blade to my neck might slip and slit me open? You bet! I like my head firmly attached to my body.

But as the minutes ticked away during my half-hour shave — Arce himself tic-ing away — it became clear he is nothing like the Demon Barber of Fleet Street.

In his chair at Tomcats Barbershop in Greenpoint, Brooklyn, Arce gave me the full treatment — a moisturizing face massage, the piles of hot towels, and a shave so close it felt fresh the next day — all while mitigating the twitchy hand that could have split open my jugular with one wrong move.

I’ve got a pretty steady hand, yet even I have cut myself with a disposable razor. But Arce drew no more than a drop of blood, typical for a super-close straight-razor shave, where the blade actually takes off the top few layers of skin.

When I got up from his chair, just two specks of red dotted my Adam’s apple.

Hours later, the red had abated, but my face stayed smooth for a good 24 hours.