You've oversimplified I think.
For Epee: The button is normally open. You need to detect Open, Closed, and Closed Against Gnd (opponent's bellguard, or grounded metal strip). Timing is also critical. Button must close for 2mS against non-gnd to score, if opponent's button also closes against non-gnd within 40mS than a double touch is scored. Touch against Gnd must set off Gnd light, button can bounce off Gnd and score. Attacker can Gnd his button and be scored upon by opponent. Attacker can be in scoring position and opponent can Gnd his button and Attacking touch will still count.
If the resistance of the blade wiring/bodycord is too high, a touch is also not allowed.
I developed a wired box and it was a lot of coding to work out a scheme to do the above, and I didn't do the resistance test because I had forgotten about it. I used alternating pulses going thru each weapon - if High/Lo was sent out on A wire and High/High was received on B wire, then button was open. If High/Lo was sent by Lo/Lo came back, button was closed but grounded. If Hi/Lo was sent and Hi/Lo came back, then button was closed and not Gnded.
How will you detect a Gnded button with wireless? That was a big stumbling block for early systems. HitMate used the capacitance of the Opponent's wire against his body to act as a Gnd plane to the Attacker's button. Didn't work well with small children. Also went thru batteries quickly.
Maybe develop a system where a frequency on the opponents bellguard can be detected in place of a simple Lo.
For Foil: The button is normally closed. Pressing a tip to opponent's Lame opens the button and is detected. Pressing a tip to opponent's bellguard sets off Gnd light. Pressing a tip to non-lame sets off Offtarget light. Timing is also different, with longer contact time required (to cut down on flicking), longer time for double touch, and there's also something about whipover, where blades are in contact and a touch is made anyway. Broken wire/unplugged wire sets off Gnd light I think.
For Sabre: Similar to foil, only there is no button. Any part of blade against opponent's lame is detected as a touch. No off target light. Touching own blade to own lame sets off off target light. Can score when opponent has own weapon touching own lame. Contact time is really small, like instantaneous. There is a whipover as well. Broken wire/unplugged wire sets off Gnd light.
I wrote my epee code between day jobs, took a few months. We were an epee only club. Never got around to foil & sabre. I talked a software engineer parent into tackling sabre, never quite got it done, there was odd delay from a touch being started to actually being signalled due to waiting for the opponent to not make a touch.
See pages 185-191
and other pages for the requirements of the scoring display.
Good luck!