I didn't stray from the commands listed on the guide for the installation of GRUB.
Replying to the edit: I mounted properly. artix-chroot works reliably without fail when booting from the livecd. Basestrap worked without fault.
Since this is on a different computer, I can't copy and paste the output. If empty, a UUID, or related to the ISO, I will omit where possible to keep it clean. I've omitted the entries under the MAJ:MIN, RM, and RO headers. RM and RO are all 0.
lsblk -l /dev/sda:
sda - 931.5G - disk
sda1 - 529M - part - the aforementioned partition made by Windows
sda2 - 863G - part - Windows
sda3 - 521M - part - Windows recovery
sda4 - 1K - part - Extended
sda5 - 62G - part - Main Linux partition, logical partition of sda4
sda6 - 2G - part - Swap partition, logical partition of sda4
lsblk -f
Name - FSTYPE - FSVER - LABEL - FSAVAIL - FSUSE% - MOUNTPOINTS
sda1 - NTFS - N/A - System Reserved
sda2 - NTFS
sda3 - NTFS
sda5 - ext4 - 1.0 - ROOT - 55.7G - 3% - /mnt
sda6 - swap - 1 - SWAP - N/A - N/A - [SWAP]