While father's vaunted healing factor.
In one of the great tragedies of his life, Wolverine accidentally abandoned his son Akihiro after the murder of his wife Itsu by the Winter Soldier. Not knowing that his unborn son would possess his healing, Logan believed the child dead, when in fact Daken was taken and raised by the villainous Romulus to kill and potentially replace his father. A lifetime of disrespect - including the canine nickname 'Daken' - instilled an immense hatred within Wolverine's son, motivating him to attempt to best his father in every way possible.
To that end, Daken sought out the fabled Muramasa blade, first seen in Daniel Way and Javier Saltares' Wolverine #40. The sword was created by the immortal swordsman Muramasa, who forged it from Logan's rage, creating a blood-red sword that slices down to the molecular level. Due to the physics-bending level on which it cuts, the Muramasa blade vastly slows healing, and has been touted as the one weapon that could actually kill Wolverine despite his powers (and indeed was used to kill a clone of Sabretooth.) With cutting-power even adamantium can't beat (and the ability to cut energy itself), the blade became Daken's prize, and Wolverine's son was eventually able to acquire a shard of the Muramasa blade, which he had bonded to the two claws that emerge from his wrists in a procedure darkly similar to Logan's experiences with Weapon X.
Thankfully, Logan was eventually able to defeat his son, cutting out his Muramasa claws and burying them at a secret location with the rest of the sword. But while this was necessary to save Daken from himself, it also deepened his hatred of Wolverine, who had stolen his chance to become the deadliest man alive and enact revenge on Romulus. This hate bubbled until Daken became a threat to Wolverine's mutant students, at which point Logan was forced to drown his son, knowing he would never stop his campaign of terror.
In his abuse at the hands of Romulus and his acquisition of the Muramasa claws, Daken walked the path of rage that defined so much of his father's life - literally wielding it as his own weapon. Daken wasn't immune to the qualities of the Muramasa metal, and had to have adamantium sheathes built into his arms to prevent accidentally wounding himself. Daken's quest and the lengths he went to in order to improve on Wolverine's claws showed how deeply he hated and wished to sur his father, even at risk to his own body, and how his own story represented what Logan's life could have been without the X-Men.
Comics being comics, Wolverine and Daken would later get a second chance at their relationship, but the Muramasa claws remain a damning metaphor for how badly Logan failed his son. Wolverine's life has always been a struggle between rage and honor, and in allowing the Muramasa blade to be forged in the aftermath of Itsu's death, he began a chain reaction of anger that turned his son into a weapon that Logan ultimately resolved to destroy.
