Morton hosted Europa League hopefuls St Johnstone in a testimonial match to honour the Englishman's 10 years of service.
In that decade, he made 399 appearances and scored 122 goals to take fifth place in the club's all-time top scorers list behind Allan McGraw, Andy Ritchie, Jimmy Gourlay and Rowan Alexander.
He took to the field with daughter Poppi for one last outing in the blue and white hoops as both teams gave him a guard of honour on a gloriously sunny day.
But, unlike many testimonial matches, this was not designed to be a light-hearted affair in which a parade of ex-team-mates would make brief cameos and the referee would award a soft penalty.
Quite the opposite, in fact, as fastidious referee Bobby Madden later proved by rigidly sticking to the rulebook and refusing to let Weatherson re-join the action in the second half.
Like whistler Madden, the managers were taking the 90 minutes seriously, with both using the outing as preparation for upcoming competitive fixtures. In that respect, Ton boss Allan Moore named a strong starting line-up which included Weatherson up front and two trialists in Dougie Imrie and Reece Hands.
Hands is a 19-year-old English central midfielder who was recently released by Blackburn Rovers, for whom he started in the first leg of the FA Youth Cup final in 2012.
New Saints manager Tommy Wright, meanwhile, takes his side to Norway for a Europa League second round qualifier against Rosenborg on Thursday and sent his men out fired up for this contest.
Their intent was underlined by ex-Ton midfielder Chris Millar, who was a man possessed in the opening stages.
With two minutes on the clock he surged down the right flank and cut back for Nigel Hasselbaink, but the former St Mirren man scooped high over the crossbar from a promising position.
He was the width of the woodwork from opening the scoring four minutes later when he latched onto David Wotherspoon's hooked pass and crashed an angled strike against the near post.
After being well and truly pinned back in their own half for the opening quarter of an hour, the hosts finally created an opening on 16 minutes.
And it was Weatherson who came within a whisker of marking the occasion with a goal when he just failed to get a touch to Imrie's dangerous inswinging cross which flashed narrowly wide of the post.
It was to be the Englishman's final contribution of the afternoon after he made way for new signing Kabba-Modou Cham on 20 minutes.
However, his near miss sparked a spell of Ton pressure in which Joe McKee pressed visiting keeper Alan Mannus into action with a swerving strike from 25 yards.
The former Bolton midfielder was growing increasingly influential, and it was he who slipped the ball to Fouad Bachirou in a promising position on the edge of the box.
Frenchman Bachirou expertly shifted the ball outside Gary McDonald to manufacture space for a strike at goal, but his rising drive narrowly cleared the crossbar.
The game hit a lull after reaching the half-hour mark and neither side managed to show the necessary craft to carve out an opening until the stroke of half-time.
It was former Scotland Under-21 Wotherspoon who created the opportunity, picking out Steven McLean with a pin-point floated centre which the striker headed woefully wide.
Wright made two changes at the break, bringing on strikers Stevie May and Rory Fallon as he switched from 4-3-3 to 4-4-2.
Moore elected to keep his powder dry until the 60-minute mark, when he introduced Tony Wallace and Archie Campbell.
Campbell took up the number 10 role behind Cham, which meant McKee dropped back into the deep-lying position beside Bachirou, just as he had against Rotherham United.
Chances were at a premium in the first 20 minutes of the second period. The match remained competitive, however, and Bachirou lit up proceedings with a dazzling piece of skill in the midfield.
Striker Cham took a while to get going, which was noted by Imrie who bemoaned his team-mate's failure to gamble when he surged to the bye-line and pulled the ball back in his direction in the first half.
But the 20-year-old started to show some of the potential, which prompted Moore to hand him a two-year deal, in the second period.
On 67 minutes he put Campbell in on goal with a perfectly-weighted pass after Wallace had flicked on a Nicolas Caraux kick-out.
In a move that has become something of a trademark for the diminutive frontman, Campbell scampered clear down the inside-right channel and unleashed a low, angled drive.
More often than not the outcome involves the ball nestling in the bottom left-hand corner of the net - but on this occasion Northern Irish goalkeeper Mannus closed the angle and made a superb block.
Caraux made a fine save of his own less than 60 seconds later when he acrobatically flipped Fallon's hooked effort from 10 yards over the top.
Fallon's strike partner May scored three times in three matches against Ton while on loan at Hamilton last season, and he was causing Ton problems again on Saturday.
On 74 minutes, it was he who was sent sprawling by Jonathan Page for the free-kick from which the deadlock was finally broken.
Saints full-back Dave MacKay was the scorer, placing a precision free-kick in the postage stamp top corner which Caraux did well to get a hand to but couldn't keep out.
Cham was starting to motor and manufactured an opening for himself when he flicked a McKee pass over his marker and then whipped round him to collect possession.
The Gambia Under-20 international - born to a father from the west African nation and a Belgian mother - rifled off a powerful angled drive which Mannus expertly turned wide.
Despite the fact this was a pre-season match the action didn't tail off in the way it can on these occasions, and Frazer Wright almost doubled the visitors' lead when he glanced a May free-kick wide.
With three minutes left to play, Weatherson's younger brothers, Paul, 20, and Daryl, 25, were brought on - and they almost provided a fairy-tale finish.
Daryl crashed an angled drive against the outside of the post in the last minute and then put brother Paul through on goal with a clever pass only for his sibling to be flagged offside.
The roof would have come off the Cowshed had either netted but in the end the Saints held on for the win.
Despite the result, it was a fitting - and emotional - send-off for a player who gave Ton a decade of sterling service.
Morton (4-2-3-1): Caraux (6); Taggart (5), Page (6), McLaughlin (7), Fitzpatrick (6); Hands (7) (Wallace 61, 4), Bachirou (8); Imrie (6) (Campbell 61, 5), McKee (7) (D. Weatherson 87, 6), O'Brien (5) (Crawford 70, 4); Peter Weatherson (6) (Cham 20, 6) (Paul Weatherson 87, 5). Subs not used: Jamieson, Russell, Gaston (gk), Knight, Verlaque.
St Johnstone (4-3-3): Mannus (7); Mackay (7), Miller (7), Wright (7), Scobbie (6); Millar (7), Cregg (6) (May 46, 6), McDonald (6) (Caddis 83, 3); Wotherspoon (6) (Edwards 65, 5), McLean (5) (Fallon 46, 6), Hasselbaink (6) (B. Easton 65, 5). Subs not used: Banks (gk), Rodger, Kane, D. Easton.
Referee: Bobby Madden