EMI Enchants The Info Tooltip

The small i badge beside the rarity line is the interesting part. Hover it and the tooltip breaks the enchantment's economy down:

• Weight - how often the enchantment is picked relative to its rivals when the game rolls an enchantment. A weight of 10 is picked ten times as often as a weight of 1.
• Anvil cost - the multiplier applied when the enchantment is combined at an anvil. This is the number that quietly makes a piece of gear "too expensive".
• Level N cost - one line per level, giving the enchanting-power window that level needs. This is why a level 3 roll refuses to appear on a table surrounded by too few bookshelves: the window has not opened yet.

Reading the per-level lines before you spend levels is the fastest way to work out whether a bookshelf or two more would change what the table offers.