Back in 2019 I converted an Imperial Knight into a Black Legion / Sons of Horus Renegade Knight it took me 18 months to revisit this build to create a close combat alternative and interchangeable weapon option, was the wait worth it?
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My first renegade Knight conversion was my Khorne one with two daemonic sculpted claws and I wanted to revisit this still but extend the claws to a giant lightning claw style, where to start. Luckily my son had started his Tyranid army and we had some spare giant scything talons and I also asked friends, Dwez and Otty if they could help, and they did. You definitely need friends when it comes to conversions and never throw anything away ;)
I added plasticard to the sided of the bladed talons to give it a mechanical look rather than an organic look and converted the Imperial edging with green stuff and plasticard. I added 8 spikes cut from spru and a chaos shield, and some guitar strings and hey presto there you go.