Knives make for multifaceted metaphors, the switchblade and the surgeon’s scalpel being fundamentally opposite sides of the same symbol. With “Machete,” her first song with a full band in roughly four years, one-time Boston music scene fixture Amanda Palmer meditates on both the blade’s ability to harm and to heal, and in the process lays out as strong a musical journey as her work on the albums “Theatre is Evil” and “Who Killed Amanda Palmer.”

We can’t embed the song on Telegram.com because of language concerns, but you can listen to it online here.

The song, which is dedicated to the late Lexington writer C. Anthony Martignetti, begins with an odd ambivalence in the face of loss, where the song’s persona wrestles with two sides of her departed friend’s life: “I have never liked the box of knives/ you said was a paradox because you’re kind,” she sings, “but withstood a childhood that robbed you blind/of love that was safe and so you learned to fight.”

There’s a lot of irony in the lyric, as Palmer immediately acknowledges the duality of the metaphor, and yet admits upfront that seeing the two sides of the metaphor doesn’t make it any easier to come to terms with. And while the song’s persona is pondering the symbolism of knives in her friend’s life, she herself is being cut: “and you took/your machete,” she sings, “and you carved out a path to my chest and you said see/there’s nothing not worth keeping.” Every laceration simultaneously hurts and heals.

Just as there’s duality in the lyrics, there’s also a double-edged dichotomy to the song’s music. “Machete” leads off with Palmer’s distinctive brand of punk cabaret — purposefully choppy and discordant at points, marked by high energy and a slightly manic pace. There’s a thick sound to the song, played by a bevy of top-notch musicians, including Palmer on piano and vocals, Jherek Bischoff on electric bass, Ben Folds on drums, Ryan Lerman on electric guitar, Aniela Marie Perry on cello, Lauren Elizabeth Baba on viola and Crystal Brooke Alforque on violin. When the song is seemingly flying ahead with reckless abandon, the affect is arresting.

But there are pivots in the song as it rapidly descends to just piano and vocals, or vocals and strings. Those moments are stirringly, heartbreakingly beautiful. It’s in these moments that Palmer lets the full-force of emotion imbued in the song have free reign, and all the sadness soaked into each note swells to the surface. The song’s real power lies in these moments of restraint, and they’re extraordinarily effective.

This is a song about a lot of things, but ultimately it’s about letting go: “you don’t need me here to cut you/free,” sings Palmer, hammering home the song’s final paradox. There’s no joy in the epiphany, just a truth that needs to cut before it heals.

Email Victor D. Infante at Victor.Infante@Telegram.com and follow him on Twitter @ocvictor.