The teeth could tear through the likes of iron and gold easily, while toxins would be restructured, rendered harmless and edible inside the body. The characteristics of whatever It's eaten, whether it be an item or another living being, would be absorbed and assimilated, so that the one that absorbed could use them as well.
Strength of the ability that was gained through absorption depends on the quality of the substance and its freshness.
On Day 80 Rou acquires the ability [Synthesis] that he uses to merge the different abilities acquired by [Absorption]. Which is quite convenient since [Absorption] starts to gather less and less abilities due to the gap of strength between Rou and most of his enemies.