The wording of Celerity (Vampire: The Dark Ages 20th, p. 202) regarding attacks per turn seems ambiguous.
How many attacks can a character with Celerity 3 make per turn?
In this iteration of Celerity (unique to Dark Ages Vampire 20th), Celerity doesn't so much give you extra actions as make you less subject to the penalties for multiple actions. As detailed on p.322, when making multiple actions in a turn…
If you wish to take multiple actions in a turn, you must decide before taking your first action. The first action is taken at +1 difficulty, and at -1 dice. Each additional action receives a cumulative +1 difficulty, and -1 dice. You cannot take an action as part of a multiple action if the difficulty would be increased to 10 or higher. Additionally, only one action per turn may be an attack action.
Emphasis added. So, if you had Celerity 3, you'd add 3 dice to your attack pools, and when you performed multiple actions in a turn, you wouldn't suffer an increase in target number until your 4th action.
The other change is that Celerity lets you circumvent the rule in italics above. Instead of being limited to a single attack action, you may make as many as half your Celerity rating, rounded up. Three halved is 1.5, which rounds up to two.
It says that "A number of these additional actions equal to half their Celerity (round up) may be attack actions." Emphasis on the additional part, as in anything other than the primary action. So that means if he chooses to use his first action to attack then the additional actions such as the second and third one come under that rule when Celerity is in its active phase. So using Celerity 3 he can make 1+(3x0.5) attacks; rounded up that means 1+2=3 attacks.