Boon Firebrand
The Minstrel's support Firebrand — Spear and Staff, mantras and tomes, and the 
Stability your squad pushes behind.
This is the boon build: no offensive stat on the gear, no damage trait on the bar. Two of your three utilities and your elite exist to put Stability on other people. The Wanderer's Firebrand is the one that also fights.
Why these traits
Indomitable Courage is the reason the build exists: it makes the third virtue break 
Stun and hand Stability to five nearby allies. 
Stalwart Speed then turns every 
Aegis or Stability you grant into 
Quickness, on multiple allies at once — your defensive output and your offensive boon output are the same button. 
Archivist of Whispers gives your virtues three extra pages and 
Loremaster generates them faster and keeps Resolve's passive running while the virtue recharges; 
Absolute Resolve makes the second virtue strip three conditions off nearby allies.
Honor pays for the rest: 
Writ of Persistence makes your symbols wider and heal allies, 
Protector's Restoration drops a symbol every time you use a healing skill, and 
Honorable Staff adds concentration and cuts 20% off the Staff cooldowns you actually press. 
Master of Consecrations exists for one skill — it stretches 
Hallowed Ground out long enough to hold a choke.
Gear reasoning
Full Minstrel's: toughness, vitality, healing power and boon duration, with nothing offensive in it. 
Water and both 
Concentration sigils stack more boon duration on top, and the infusions are healing and concentration. The consumables do the same job — 
Mint Creme Brulee is +100 concentration, +70 healing power and +10% outgoing healing, and 
Peppermint Oil converts 6% of that healing power and 3% of your precision back into yet more concentration. Every point on the character goes into making your boons land longer on other people.
Frenzy pulls two seconds off every skill on your bar when you kill someone. 
Energy returns half your endurance on weapon swap, which matters because 
Selfless Daring heals nearby allies at the end of every dodge. 
Febe fires off your healing skill: 
Swiftness for nearby allies and movement-impairing conditions removed from them, which is what gets a squad out of a bad spot.
When not to run it
If the squad already has its Stability covered and what it is short of is damage, this build adds almost none — the gear has no power on it at all. The Wanderer's Firebrand on the Firebrand hub is the one that covers two roles at once, and Dragonhunter is the one that just hits. Luminary covers the same support slot with a steadier rhythm; Firebrand is the pick when you want tomes you can open on demand.