How do the Attack Boost bonuses from Foods and Elixirs work?

So I just tested this using the method suggested by @Seiyria.

These following results are gathered while wearing the Champions Tunic, and using each tier of food against the same enemy at full health.

+--------------------+----------+----+----+----+
|       Weapon       | Standard | T1 | T2 | T3 |
+--------------------+----------+----+----+----+
| Torch              |        2 |  2 |  2 |  3 |
| Woodcutters Axe    |        3 |  3 |  3 |  4 |
| Throwing Spear     |        6 |  7 |  7 |  9 |
| Iron Sledgehammer  |       12 | 14 | 15 | 18 |
| Guardian Sword     |       20 | 24 | 26 | 30 |
| Knights Broadsword |       26 | 31 | 33 | 39 |
| Guardian Sword+    |       30 | 36 | 39 | 45 |
| Guardian Sword++   |       40 | 48 | 52 | 60 |
| Ancient Battleaxe++|       60 | 72 | 78 | 90 |
+--------------------+----------+----+----+----+

As indicated by this data, the Percentual Increases are:

• Tier 1 - 20%
• Tier 2 - 30%
• Tier 3 - 50%

(after rounding)