I avoid completing the Obelisk quest and Zoltan Phelps' quest to find Mordred, and I don't take Excalibur from its stone, until I have collected 13 artifacts and relics from other sources.Among the 13 I look for are second copies of the three Obelisk Quest items (Morgan, Guinevere, and Igraine), together with:
Galahad (AC36 mail armour of Protection, +25 HP),
Pendragon (AC11 cloak, of Thievery, +30 Luck, immumity to poison),
Hades (3d3 + 15 sword, +20 poison damage, +20 luck, of Thievery, BUT negative regeneration),
Ares (2d4 + 14 mace, +30 fire damage, +25 fire resistance - the only relic without a drawback)
Poseidon (2d6 + 15 spear, +20 might, +20 endurance, +20 accuracy, BUT -10 AC, -10 speed)
Artemis (5d2 + 12 bow, +20 electrical damage BUT -10 to all resistances)
Apollo (44AC mail armour, +20 all resistances, +20 luck BUT -30 endurance)
I seldom bother collecting Excalibur. My standard party is ACSS, so I arm my archer with Hades and Poseidon and there's no-one else who can use a sword. I avoid Chronos, Hercules, Zeus, Atlas, Aphrodite, Athena, and Hera, considering that the negatives outweigh the positives, although I would take Zeus if my party included a paladin.