Broken swords and spearheads were found by archaeologists on the RSPB Scotland nature reserve.
Twelve pieces excavated from several different weapons have been handed over to Kilmartin Museum in Argyll.
RSPB Scotland reserves archaeologist Jill Harden said they had probably been deliberately broken and thrown into a loch as part of a religious ceremony.
"This is the first discovery of this size from Argyll for many years," she said.
"The items were recovered from what had once been a freshwater loch - it seems that they had been purposely broken and cast into the waters as part of a ceremony, most likely as offerings or gifts to the gods or goddesses of the time.
"It is recorded that bronze swords were found on Coll in the 19th Century during drainage works, but their whereabouts today are unknown."
The archaeological investigation was directed by the Treasure Trove Unit, National Museums Scotland and RSPB Scotland.
Trevor Cowie, from National Museums Scotland's department of Scottish history and archaeology, said: "While a fair number of objects from this period have been discovered in the west of Scotland in the past, we generally know very little about the precise places where they were found.
"Archaeological techniques have developed dramatically since those 19th Century discoveries were made, so we have a great opportunity here to resolve many unanswered questions about life on Coll some 3,000 years ago."
The weapons can be viewed at the the Isle of Coll's An Cridhe community centre on Thursday and Friday.
Bronze weapons believed to date back about 3,000 years have been discovered on the Isle of Coll.