It's Xiang Shu's sword (thumbs up) he gets it somewhere in the 20's chapters... when they went to Chang'an. The reason I gave different names is because uh the translations can sometimes have... so it shows up as 不动如山 (budong rushan) but ended up translated as Wisdom Sword, Sword of Wisdom or Acala Blade (Budong Mingwang is CN for Acala). I think at some point the novel tl for Dinghai had it as Acala Blade but switched back to Wisdom Sword...? The Tianbao donghua official subs went with Sword of Wisdom, I think.