Relic +1 or ?????

[Sinth]

Relic + 1.

Weapon damage will always be better than any other stat for DPS.

Unless the primary stat bonus from the other gear exceeds the flat DPS gain from the weapon, such as Wyrm Mail piece for DRGs.
Gae Bolg +1: +2 flat damage +4 STR +3 Crit +4 VIT (over base relic stats)
Wyrm's Mail: +9 STR +6 DET +11 VIT +24 Crit -19 Skill speed (over Darklight Cuirass)

The Wyrm's mail choice will net slightly higher DPS, as the STR + DET + CRIT > Flat DPS + STR gained in both items respectively. Additionally, the Wyrm's mail choice provides more durability through higher defense, determination, and vitality. A stronger weapon does not necessarily mean more DPS when compared with other gear slot gains.

[EasymodeX]

Unless the primary stat bonus from the other gear exceeds the flat DPS gain from the weapon, such as Wyrm Mail piece for DRGs.
Gae Bolg +1: +2 flat damage +4 STR +3 Crit +4 VIT (over base relic stats)
Wyrm's Mail: +9 STR +6 DET +11 VIT +24 Crit -19 Skill speed (over Darklight Cuirass)

2 WD's worth about 15 str. Gae Bolg +1 > Wyrm's Mail in that comparison.

Unless you really want the HP from the Vit really badly, or the 19 skill speed on the DL chest is putting you over 200 skill speed and you want to remove it.

Or some other weird situation.