create a USB-Key, install extlinux onto it. In extlinux.conf, you can provide kernel cmdline, with root=UUID=xxx-xxx-xxx-xxx In that way, you can boot your archlinux(and any other linux) from USB, and using your main HDD(partition) as the rootfs.
Note, every time you update the kernel, you must copy the updated vmliuz + initramfs.img into you USB disk.
That is not a LIVE USB-Key, it just an bootable kernel + initramfs. Not a completed OS.
You can do that just in case but I don't think it will be necessary. I am using Arch for years now in 3 different UEFI computers with Windows 10. Just follow the installation guide and boot loader wiki page. Just like Jason and Artur linked, wiki warns you for possible problems before you face them and suggests fixes. In case you wonder, I am using systemd-boot with (almost) default configs. Never used GRUB with Arch but it doesn't cause any problems on other Linux distros (at least for me) with Windows 10 dual boot so it is a safe bet too.