There are two useful fighters guild abilities for a mag Sorc.

In PvE Rearming trap can be a good source of minor force. The damage from the skill itself won’t scale all that well assuming you stack into magic and spell damage (as you should), but the buff is very strong. You can now also get the same buff from the psijic line which is probably a better option most of the time.

In pvp, a lot of magic sorcs slot dawnbreaker of smiting for a cheap and fast ultimate. It plays well into the toolkit of trying to line up quick burst combos.

Both of these have the downside of forcing you into melee range. Certainly none of the skills are mandatory. Staffs do not do physical damage. They do elemental damage of their specific type and boost the spell damage stat when equipped.

Most skills scale of either max magic and spell damage and cost magic OR max stamina and weapon damage and cost stamina. With very few exceptions, you should pick one avenue and go all in. As a staff wielding Sorc you should prioritize a high magic pool followed by high spell damage, and generally use skills that cost magic.