Try harder to convince them to mail it to you.
Really, whoever told you/them they can't send it by post is mistaken. As Rob pointed out in the comments, these tools are not regulated at all in the Netherlands. You can easily order one online and have it sent to you. (You can also order an entire set of kitchen knives and PostNL won't have any trouble delivering it.)
The PostNL list of items prohibited in international mail doesn't ban knives in general, only those that are "weapons" as defined by the relevant Dutch Arms and Ammunition act (the English version of that list is perhaps a little ambiguous but the Dutch version is not. It clearly says "Weapons that fall under the Arms and Ammunition act" (translation mine).
The relevant bit of that act (Wet wapens en munitie) which defines what is a weapon is Article 2:
- 1°. stiletto’s, valmessen en vlindermessen;
- 2°. andere opvouwbare messen, indien:
- a. het lemmet meer dan een snijkant heeft; of
- b. de lengte in opengevouwen toestand langer dan 28 cm is;
- 1°. blanke wapens waarvan het lemmet meer dan een snijkant heeft, voor zover zij niet vallen onder categorie I;
- 2°. degens, zwaarden, sabels en bajonetten;
My (mostly literal) translation:
- stilettos, switchblades, butterfly knives
- other folding knives, in case:
- a. the blade has more than one cutting edge, or
- b. the length in the unfolded state is greater than 28 cm
- cold weapons having a blade with more than one cutting edge, unless they fall under Category I;
- swords, sabres, bayonets
IANAL, but I would say your Leatherman clearly does not fall under this definition, thus it is not a weapon controlled by this act (if it was, you would likely have trouble getting it into the country in the first place), and thus it is permitted in international mail.