Ace's baseball bat

Ace often carried a baseball bat in her rucksack and used it as a weapon. Its power was enhanced by the Hand of Omega, allowing it to damage even Dalek casings.

Ace's weapon
Ace engaged in a bar fight at Bonjaxx's Bar on Maruthea with her bat, clobbering a Sontaran and the Kandyman. (COMIC: Party Animals)

In 1963 Shoreditch, the Seventh Doctor used the Hand of Omega to enhance the bat's offensive capabilities and render it effective against Daleks. It was later destroyed when the Doctor used it to cripple the Imperial Daleks' Transmat device, an act that put too much stress on the already weakened bat. (TV: Remembrance of the Daleks)

Hex found Ace's baseball bat from her time at school, which led Hex and Ace to realise they were still in the Celestial Toymaker's world. (AUDIO: The Magic Mousetrap)

New owners
The Eighth Doctor gave Izzy Sinclair a baseball bat which she used to smash the Threshold's control centre. The Doctor said "the bat's previous owner would be proud". (COMIC: Wormwood)

Retained by Ace
By other accounts, Ace kept her bat after she left the Seventh Doctor (PROSE: At Childhood's End, TV: The Power of the Doctor) because, as a parting gift, the Doctor fixed the bat when he and Ace finally parted ways.

Ace kept it in her office at the A Charitable Earth headquarters. She used it to fight the Ratts, but they abducted her and took her to Peerie Canto. However, the Thirteenth Doctor was able to trace the bat's energy due to it having been enhanced by the Hand of Omega. Ace left her bat when she was taken by Halogi-Kari, but Ryan Sinclair found it and used it to free Chantelle and other abductees. Ace then used it to incapacitate Halogi-Kari. (PROSE: At Childhood's End)

By another account, Ace met the Thirteenth Doctor in 2022 during the events of the Master's Dalek Plan. She used it to damage a bronze Dalek before causing it to explode with Nitro-999. (TV: The Power of the Doctor)