I can't find anything in the SM Codex regarding the auxiliary grenade launcher, which according to Forgeworld's Badab character pdf ([url]http://www.forgeworld.co.uk/Downloads/Product/PDF/B/badabupdate-v2.pdf[/url] - Enkomi is on the last page) the Minotaurs chaplain Ivanus Enkomi comes equipped with.
The closest I can find in the Codex is the Astartes grenade launcher. I'm very new to the game, so I'm wondering if I substitute the rules for the Astartes GL for the presumably now-defunct Auxiliary GL? If so, why would I pay an extra 10 points for the Crozius Arkanos when all I'm really getting for those points is a seemingly less effective GL, losing the +2S granted by a regular crozius and gaining Master Crafted.
I'd be really grateful for any advice, sorry if I'm missing something obvious.