He doesn’t nearly have the skills to use it, so I suggest he doesn’t buy it at all.
Try to skill up with the lowest requirement knife you can find (TT knife) until you max the Armatrix SB-10.
Then work your way up to the next Armatrix.
Do this until you have the skills for Aakas Fire Dagger, then use that until you can use the Sonkra, then use that to skill towards ArcSpark.
From there on you’re on your own and also probably a year older ;-)