Medieval crossbow modeled in Tinkercad, with variant trigger design.

This mostly came about as an extension of modeling a crossbow nut so i could machine it during the open lab of my machining class, so i thought i'd model the rest of it so i'd have more exact dimensions for the trigger and whatnot. 

The second design came about as an idea to get away from tracking down 3/8 square stock and some way to bend it, while it still uses 3/8 square stock in this model, it gets away from the large zig-zag bend most designs have, allowing for and unbent primary lever, and a secondary lever under much less strain to the point it could be made from wood even. These are connected by a simple sliding pin. I speculate canting this pin backwards may be helpful, giving you a longer, but lighter trigger pull. A single compression spring could be used for both levers by simply drilling through the wood between them ahead of the privet for the primary lever and behind that of the secondary lever, and would be held captive by the secondary lever once attached. Like a pinlock design, some means would be needed to keep the lever from rotating too far away from the stock. A similar modification could be made to a claplock design as well. Also credit to the plans on alcheminc.com, which inspired the design. 

The model is publicly available here.

Your second idea is really nice, but the "sliding pin" needs a "return spring" on top of the sear lever to push everything back into proper position to cock for the next shot

I'm aware of this, a single coil spring could be used to spring load both levers if placed vertically between the pivots. A few other places could work for either leaf springs or coil springs, but i generally leave them out of designs, partly because springs are hard to model, and partly because i simply use what springs i have laying around, or make them from old saw blades. 

Also an idea: This second design would allow the trigger to slide forward while either locked, or set so it would be locked when pushed into the string, meaning this trigger design could work for a crossbow with a cocking mechanism where the whole trigger mechanism slid forward then back with the string. I'm not exactly a fan of this design, but i'm sure i've seen a crossbow with it somewhere.