1) yeah, sounds like you need a better holster: even if the lanyard keeps you from losing it, the gun can still get damaged if it falls out and hits a rock or a concrete floor;
2) the 5.2R looks like it has a Hi-Capa frame. The WE Hi-Capa was (probably still is) a clone of the TM one and parts should be compatible. So you need to get a hammer spring housing with a lanyard loop (the hammer spring housing is the block on the back edge of the grip).
Something like http://www.ebairsoft.com/hammer-spri...ck-p-2441.html
(comments has someone who said they installed it on a WE) or http://shop.ehobbyasia.com/nine-ball...l#.U3v5ZfldVCA
. Those are examples, there are other brands and other stores to choose from; you'll have to do your own shopping.